Greentown Labs and MassChallenge have formed a strategic partnership. Photo courtesy Greentown Labs.

Climatetech incubator Greentown Labs has formed a strategic partnership with global zero-equity accelerator MassChallenge.

The two organizations have headquarters in the Boston area, while Greentown Labs is also co-located in Houston. MassChallenge has a hub in Dallas, as well as others in Israel, Switzerland and the United Kingdom.

The new partnership aims to strengthen the ecosystem for early-stage climatetech startups by providing more mentorship, support and a broader commercialization network for members, according to a news release.

Greentown Labs will share its expertise with the 23 startups in MassChallenge's first climate-specific accelerator, known as the MassChallenge Early Stage Climate program. Additionally, Greentown Labs members will benefit from MassChallenge's network of expert mentors, judges, entrepreneurs, partners, investors, philanthropists and others.

“There are so many synergies and shared values between MassChallenge and Greentown that launching a collaboration like this feels like a natural next step for our organizations as we strive to support as many early-stage climate founders as possible,” Georgina Campbell Flatter, Greentown Labs CEO, said in the news release. “We want to reduce the friction and barriers to market for these climate entrepreneurs and ultimately increase their opportunity for success—ecosystem collaboration is an essential part of solving these challenges together.”

Combined, Greentown and MassChallenge report that they have supported more than 4,500 founders and more than 1,000 climate startups. MassChallenge has awarded more than $18 million in equity-free grants to startups, which have gone on to raise over $15 billion, since it was founded in 2009. Greentown Labs has helped more than 575 startups raise more than $8.2 billion in funding since it launched in 2011.

Greentown recently added five startups to its Houston community and 14 other climatetech ventures to its Boston incubator. It also announced its third ACCEL cohort, which works to advance BIPOC-led startups in the climatetech space, earlier this year. Read more here.

Five companies have joined Greentown Labs Houston, specializing in various "green" applications, from converting plastic waste into sustainable materials to developing energy-storage solutions. Photo courtesy Greentown Labs.

Greentown Labs announces newest startups to join Houston climatetech incubator

green team

Greentown Labs announced that it added five startups to its Houston community in Q1 of 2025.

The companies are among a group of 19 that joined the climatetech incubator, which is co-located in Houston and Boston, in the same time period. The companies that joined the Houston-based lab specialize in a number of "green" applications, from converting plastic waste into sustainable materials to developing energy-storage solutions.

The new Houston members include:

  • Concept Loop, a project of Pakistan-based Innova8e Inc., aims to repurpose post-industrial and post-consumer plastic waste into sustainable building materials.
  • GeoFuels, a Sugar Land-based company that produces hydrogen by using baseload geothermal power and methane pyrolysis.
  • PLASENE, a Houston-based company with an innovative platform that converts plastic waste into liquid fuel and low-carbon hydrogen through its proprietary catalysts and modular, scalable, pre-engineered units platform. The company was named to Greentown's ACCEL Year 3 cohort earlier this year.
  • RepAir Carbon, an Israeli company with a fully electric, zero-heat carbon-removal technology that consumes minimal energy, operates without liquids or solvents, and produces no hazardous materials or waste.
  • RotorVault from Pasadena, California, is commercializing energy-storage and load-following solutions that are containerized, modular, and field-deployable systems built on flywheel technology.

Fourteen other companies will join Greentown Boston's incubator. See the full list here.

PLASENE and five other new members—Thola, Respire Energy, Andros Innovations, FAST Metals and Tato Labs—join Greentown Labs through its most recent Advancing Climatetech and Clean Energy Leaders Program, or ACCEL, cohort. ACCEL, which works to advance BIPOC-led startups in the climatetech space, announced its third cohort last month.

From potato-starch-based bioplastics startups to companies developing carbon-coated silicon anodes, here's who's joining Greentown Labs and Browning the Green Space's ACCEL program. Photo via browningthegreenspace.org

2 Houston startups join Greentown Labs' BIPOC-led accelerator program

seeing green

Greentown Labs and Browning the Green Space announced the newest cohort for its Advancing Climatetech and Clean Energy Leaders Program, or ACCEL, which works to advance BIPOC-led startups in the climatetech space.

Two Houston companies and one from Austin are among the eight startups to be named to the 2025 group.

“The startups selected for the third ACCEL cohort represent a phenomenal range of energy and climatetech innovations, which underscores our belief that everyone and many solutions must play a role in our community’s collective decarbonization efforts,” Georgina Campbell Flatter, Greentown’s new CEO, said in a release. “We’re proud to welcome these entrepreneurs to our community and eager to see all they’ll achieve throughout the program and beyond!”

Each of the early-stage startups within the cohort will receive $25,000 in non-dilutive grant funding and participate in the year-long program focused on product and technology development, market development, fundraising and management, and team development, according to Greentown. The curriculum is led by VentureWell, a nonprofit with expertise in venture development in climatetech.

The Houston companies include:

  • Carbonext, founded by Olanrewaju Tanimola. The company is leveraging its proprietary, off-the-shelf 3D-graphene technology to develop integrated solutions with carbon-coated silicon anodes to address challenges in the graphite ecosystem, as well as lithium-battery anodes.
  • PLASENE, founded by Sohel Shaikh, Alper Gulludag and Romolo Raciti. The company offers an innovative platform that converts plastic waste into liquid fuel and low-carbon hydrogen through its proprietary catalysts and modular, scalable, pre-engineered units

The remaining six companies are:

  • Inductive Robotics, founded in Austin by Madhav Ayyagari and David Alspaugh. The startup deploys autonomous robots that deliver EV charging directly to parked vehicles in commercial parking facilities, using a subscription-based model.
  • Andros Innovations, founded in Cambridge, Massachusetts by Laron Burrows. The startup has developed a reactor that produces ammonia more cheaply, cleanly and safely than traditional methods do.
  • FAST Metals, founded in Worcester, Massachusetts by Sumedh Gostu and Anthony Staley. It has developed a hydrometallurgical-recovery process capable of extracting iron, aluminum, scandium, titanium, and other rare-earth elements from industrial tailings.
  • Respire Energy, founded in Boston by Dave Hsu, Xiaowei Teng, and Candy Wong. The energy storage startup has developed a safe, low-cost, and long-duration metal-air battery designed for microgrids.
  • Tato Labs, founded in Brooklyn by Mecca McDonald and Mia Dunn. It is developing scalable, innovative, bioplastic products and packaging solutions that leverage potato starch, protect and preserve the natural ecosystem, and minimize plastic waste.
  • Thola, founded in Portland, Maine, by Nneile Nkholise and Lerato Takana. The company provides an on-demand marketplace for commercial-building sustainability and safety management, with a mission to decarbonize old buildings.

ACCEL is supported by the Massachusetts Clean Energy Center (MassCEC), Shell, Equinor, the Growth Capital Division of MassDevelopment, Microsoft and the Barr Foundation.

The accelerator has supported 13 early-stage startups since it was founded in 2023, resulting in $325,000 in grant funding. Houston companies have been represented in each cohort. Click here to see the 2024 cohort and here to see the inaugural 2023 cohort.

The seven selected startups will have year-long curated curriculum, incubation at Greentown's two locations, a non-dilutive $25,000 grant, and access to mentors, corporates, and more from both Greentown and BGS's networks. Photo via browningthegreenspace.org

Greentown Labs names latest cohort of BIPOC-led climatetech startups

browning the green space

Two organizations have named the seven startup participants for their accelerator that works to advance BIPOC-led startups in the climatetech space.

Greentown Labs and Browning the Green Space named the newest accelerator for the Advancing Climatetech and Clean Energy Leaders Program, or ACCEL. The seven selected startups will have year-long curated curriculum, incubation at Greentown's two locations, a non-dilutive $25,000 grant, and access to mentors, corporates, and more from both Greentown and BGS's networks.

"Building on the momentum and success of our inaugural year, Greentown Labs is proud to welcome this incredible cohort of BIPOC-led startups to Year 2 of ACCEL," Greentown Labs CEO and President Kevin Knobloch says in a news release. "These founders and their teams are developing a dynamic array of much-needed climatetech solutions, and we're privileged to support them on their startup journeys as they advance their technologies and grow their teams."

The 2024 cohort includes:

  • AtmoSpark Technologies, based in Houston, is an atmospheric water generation company with a patented electro-condensation technology, which has a lower energy footprint than that of current water-generation methods.
  • Cambridge, Massachusetts-based Aquasaic is harnessing biology to clean water for planetary and human health.
  • Houston-based Axis Sky Renewablescreates innovative wind solutions, specializing in vertical-axis wind turbines that are less expensive to produce, deploy, and maintain than traditional wind turbines.
  • Carbon Negative Solutions, from Rock Hill, New York, is creating smart-city-ready, carbon-negative concrete products.
  • NYC-based Cellsense develops interactive bio-embellishments that create new possibilities for designers while eliminating microplastics and replacing fossil-fuel-based material at scale.
  • EcoForge, headquartered in Providence, Rhode Island, is a building-material technology company developing affordable, high-performance building materials from local agricultural residues, replacing energy-intensive, fossil-based materials.
  • Boston-based Sankofa Dynamics creates low-cost, eco-friendly solutions for water, air, and energy problems.

The program is supported by the Massachusetts Clean Energy Center,Microsoft's Climate Innovation Fund, Equinor, Barr Foundation.

"These BIPOC-led startups are developing climate technologies that will lead us to a more equitable and sustainable future," MassCEC CEO Dr. Emily Reichert, the former CEO of Greentown, says in the release. "We want ALL climatetech innovators and entrepreneurs to thrive here in Massachusetts. We are proud to support the ACCEL accelerator, created and led by Greentown Labs and Browning the Green Space. The ACCEL program is helping us build a more diverse innovation ecosystem by breaking down barriers and expanding opportunities."

ACCEL was announced in 2022, and the first cohort featured six climatetech startups — two based in Houston.

"Our second year of ACCEL brings together an inspirational and diverse cohort of seven BIPOC-led startups developing tech to accelerate the distribution of climate solutions that address community needs," Browning the Green Space President and Executive Director Kerry Bowie adds. "We are thrilled to continue to strengthen our partnership with Greentown Labs and VentureWell and build on the learnings from the pilot cohort to provide critical support infrastructure for entrepreneurs of color."

The ACCEL program kicks off at an event on March 6 at Greentown's Boston location.

The Houston Ion District Investor Activation Program is open to accredited investors and free to join. Photo via GreentownLabs.com

Greentown Houston announces new investor program to increase equity in climatetech funding

calling all funders

Greentown Labs has announced a new program to address inequity and unavailability of funding for early-stage climatetech startups.

The Houston Ion District Investor Activation Program is supported by a Build to Scale Capital Challenge grant from the U.S. Economic Development Administration, open to accredited investors, and free to join.

Participating investors will have access to curated startup introductions based on preferred stage, industry, check size, and more, plus access to information on startups and investor-specific newsletters featuring Greentown startups invite-only events.

"This program brings early-stage investors from Greater Houston into the fold, offering education on climatetech investing, channeling a pool of capital to young startups, and catalyzing a thriving climatetech investment ecosystem that prioritizes diversity, equity, and inclusion," reads the email announcing the program.

Members will also get networking opportunities with fellow investors and leading climatetech startups, which includes investor roundtables. Sector Pitch Days, and more Educational workshops on climatetech investing run by Vinson & Elkins, and more will be made available. The new initiative is meant “ to strengthen Houston’s energy-transition ecosystem” according to a news release.

In 2023, Greentown Labs helped 87 corporate partners, and collaborated with over 70 Houston startups. Some of their members recently achieved success in their respective fields.

The future of the oil and gas workforce isn't looking too bright when it comes to recruiting, the Wall Street Journal reports. Photo via Getty Images

Report: College enrollment in petroleum programs — including in Texas — sees historic drop

looking forward

Student enrollment in petroleum engineering programs at universities — including Texas schools — has dropped significantly, according to a recent report.

This prospective energy workforce is concerned about job security as the industry moves forward in the energy transition, reports the Wall Street Journal. The number of students enrolled in petroleum engineering programs has decreased to its lowest point in a decade, the WSJ found, breaking the typical cycle, which "ebbed and flowed" alongside the price of oil.

This decline is estimated as a 75 percent drop in enrollment since 2014, Lloyd Heinze, a Texas Tech University professor, tells the WSJ. The article specifies that the University of Texas at Austin has seen a 42 percent decline since its peak enrollment in 2015, and Texas A&M University has dropped 63.3 percent. Both schools' petroleum engineering programs are ranked No. 1 and No. 2, respectively, by U.S. News and World Report. Texas Tech, which ties with the University of Houston at No. 9 on the U.S. News report, has seen a 88.1 percent decline since its peak in 2015. UH data wasn't included in the article.

The article highlights declines at Colorado School of Mines (87.7 percent), Louisiana State University (89 percent), and University of Oklahoma (90 percent) since their peak enrollment in 2015.

A decline in future workforce for the energy industry would directly affect Houston's economy. According to the 2023 Houston Facts report from the Greater Houston Partnership, Houston held 23.8 percent of the nation’s jobs in oil and gas extraction (33,400 of 140,200) 17.0 percent of jobs in oil field services (33,600 of 198,100), and 9.6 percent of jobs in manufacturing of agricultural, construction and mining equipment (20,400 of 212,000), based on data from the U.S. Bureau of Labor Statistics.

Barbara Burger tells the WSJ that new climatetech-focused startups have emerged and become more attractive to both college graduates and current oil and gas workforce. “There’s competition in a way that probably wasn’t there 15 years ago,” she shares.

The lack of college student pipeline paired with the diminishing workforce from emerging companies poses a challenge to incubant energy corporations, many of which have invested in programs at schools to better attract college graduates. The WSJ article points to BP's $4 million fellowship program with U.S. universities announced in February.

Just this week, Baker Hughes granted $100,000 to the University of Houston's Energy Transition Institute, which was founded last year with backing from Shell. In a recent interview with EnergyCapital, Joseph Powell, founding director of UH Energy Transition Institute, explains how the institute was founded to better engage with college students and bring them into the transitioning industry.

"It takes a lot of energy to process chemicals, plastics, and materials in a circular manner," he says. "Developing that workforce of the future means we need the students who want to engage in these efforts and making sure that those opportunities are available across the board to people of all different economic backgrounds in terms of participating in what is going to be just a tremendous growth engine for the future in terms of jobs and opportunities."

Clean energy jobs are already in Texas, and are ripe for the taking, according to a recent SmartAsset report that found that 2.23 percent of workers in the Houston area hold down jobs classified as “green.” While oil and gas positions are still paying top dollar, these clean energy jobs reportedly pay an average of 21 percent more than other jobs.

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Rice research team's study keeps CO2-to-fuel devices running 50 times longer

new findings

In a new study published in the journal Science, a team of Rice University researchers shared findings on how acid bubbles can improve the stability of electrochemical devices that convert carbon dioxide into useful fuels and chemicals.

The team led by Rice associate professor Hoatian Wang addressed an issue in the performance and stability of CO2 reduction systems. The gas flow channels in the systems often clog due to salt buildup, reducing efficiency and causing the devices to fail prematurely after about 80 hours of operation.

“Salt precipitation blocks CO2 transport and floods the gas diffusion electrode, which leads to performance failure,” Wang said in a news release. “This typically happens within a few hundred hours, which is far from commercial viability.”

By using an acid-humidified CO2 technique, the team was able to extend the operational life of a CO2 reduction system more than 50-fold, demonstrating more than 4,500 hours of stable operation in a scaled-up reactor.

The Rice team made a simple swap with a significant impact. Instead of using water to humidify the CO2 gas input into the reactor, the team bubbled the gas through an acid solution such as hydrochloric, formic or acetic acid. This process made more soluble salt formations that did not crystallize or block the channels.

The process has major implications for an emerging green technology known as electrochemical CO2 reduction, or CO2RR, that transforms climate-warming CO2 into products like carbon monoxide, ethylene, or alcohols. The products can be further refined into fuels or feedstocks.

“Using the traditional method of water-humidified CO2 could lead to salt formation in the cathode gas flow channels,” Shaoyun Hao, postdoctoral research associate in chemical and biomolecular engineering at Rice and co-first author, explained in the news release. “We hypothesized — and confirmed — that acid vapor could dissolve the salt and convert the low solubility KHCO3 into salt with higher solubility, thus shifting the solubility balance just enough to avoid clogging without affecting catalyst performance.”

The Rice team believes the work can lead to more scalable CO2 electrolyzers, which is vital if the technology is to be deployed at industrial scales as part of carbon capture and utilization strategies. Since the approach itself is relatively simple, it could lead to a more cost-effective and efficient solution. It also worked well with multiple catalyst types, including zinc oxide, copper oxide and bismuth oxide, which are allo used to target different CO2RR products.

“Our method addresses a long-standing obstacle with a low-cost, easily implementable solution,” Ahmad Elgazzar, co-first author and graduate student in chemical and biomolecular engineering at Rice, added in the release. “It’s a step toward making carbon utilization technologies more commercially viable and more sustainable.”

A team led by Wang and in collaboration with researchers from the University of Houston also shared findings on salt precipitation buildup and CO2RR in a recent edition of the journal Nature Energy. Read more here.

The case for smarter CUI inspections in the energy sector

Guest Column

Corrosion under insulation (CUI) accounts for roughly 60% of pipeline leaks in the U.S. oil and gas sector. Yet many operators still rely on outdated inspection methods that are slow, risky, and economically unsustainable.

This year, widespread budget cuts and layoffs across the sector are forcing refineries to do more with less. Efficiency is no longer a goal; it’s a mandate. The challenge: how to maintain safety and reliability without overextending resources?

Fortunately, a new generation of technologies is gaining traction in the oil and gas industry, offering operators faster, safer, and more cost-effective ways to identify and mitigate CUI.

Hidden cost of corrosion

Corrosion is a pervasive threat, with CUI posing the greatest risk to refinery operations. Insulation conceals damage until it becomes severe, making detection difficult and ultimately leading to failure. NACE International estimates the annual cost of corrosion in the U.S. at $276 billion.

Compounding the issue is aging infrastructure: roughly half of the nation’s 2.6 million miles of pipeline are over 50 years old. Aging infrastructure increases the urgency and the cost of inspections.

So, the question is: Are we at a breaking point or an inflection point? The answer depends largely on how quickly the industry can move beyond inspection methods that no longer match today's operational or economic realities.

Legacy methods such as insulation stripping, scaffolding, and manual NDT are slow, hazardous, and offer incomplete coverage. With maintenance budgets tightening, these methods are no longer viable.

Why traditional inspection falls short

Without question, what worked 50 years ago no longer works today. Traditional inspection methods are slow, siloed, and dangerously incomplete.

Insulation removal:

  • Disruptive and expensive.
  • Labor-intensive and time-consuming, with a high risk of process upsets and insulation damage.
  • Limited coverage. Often targets a small percentage of piping, leaving large areas unchecked.
  • Health risks: Exposes workers to hazardous materials such as asbestos or fiberglass.

Rope access and scaffolding:

  • Safety hazards. Falls from height remain a leading cause of injury.
  • Restricted time and access. Weather, fatigue, and complex layouts limit coverage and effectiveness.
  • High coordination costs. Multiple contractors, complex scheduling, and oversight, which require continuous monitoring, documentation, and compliance assurance across vendors and protocols drive up costs.

Spot checks:

  • Low detection probability. Random sampling often fails to detect localized corrosion.
  • Data gaps. Paper records and inconsistent methods hinder lifecycle asset planning.
  • Reactive, not proactive: Problems are often discovered late after damage has already occurred.

A smarter way forward

While traditional NDT methods for CUI like Pulsed Eddy Current (PEC) and Real-Time Radiography (RTR) remain valuable, the addition of robotic systems, sensors, and AI are transforming CUI inspection.

Robotic systems, sensors, and AI are reshaping how CUI inspections are conducted, reducing reliance on manual labor and enabling broader, data-rich asset visibility for better planning and decision-making.

ARIX Technologies, for example, introduced pipe-climbing robotic systems capable of full-coverage inspections of insulated pipes without the need for insulation removal. Venus, ARIX’s pipe-climbing robot, delivers full 360° CUI data across both vertical and horizontal pipe circuits — without magnets, scaffolding, or insulation removal. It captures high-resolution visuals and Pulsed Eddy Current (PEC) data simultaneously, allowing operators to review inspection video and analyze corrosion insights in one integrated workflow. This streamlines data collection, speeds up analysis, and keeps personnel out of hazardous zones — making inspections faster, safer, and far more actionable.

These integrated technology platforms are driving measurable gains:

  • Autonomous grid scanning: Delivers structured, repeatable coverage across pipe surfaces for greater inspection consistency.
  • Integrated inspection portal: Combines PEC, RTR, and video into a unified 3D visualization, streamlining analysis across inspection teams.
  • Actionable insights: Enables more confident planning and risk forecasting through digital, shareable data—not siloed or static.

Real-world results

Petromax Refining adopted ARIX’s robotic inspection systems to modernize its CUI inspections, and its results were substantial and measurable:

  • Inspection time dropped from nine months to 39 days.
  • Costs were cut by 63% compared to traditional methods.
  • Scaffolding was minimized 99%, reducing hazardous risks and labor demands.
  • Data accuracy improved, supporting more innovative maintenance planning.

Why the time is now

Energy operators face mounting pressure from all sides: aging infrastructure, constrained budgets, rising safety risks, and growing ESG expectations.

In the U.S., downstream operators are increasingly piloting drone and crawler solutions to automate inspection rounds in refineries, tank farms, and pipelines. Over 92% of oil and gas companies report that they are investing in AI or robotic technologies or have plans to invest soon to modernize operations.

The tools are here. The data is here. Smarter inspection is no longer aspirational — it’s operational. The case has been made. Petromax and others are showing what’s possible. Smarter inspection is no longer a leap but a step forward.

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Tyler Flanagan is director of service & operations at Houston-based ARIX Technologies.


Scientists warn greenhouse gas accumulation is accelerating and more extreme weather will come

Climate Report

Humans are on track to release so much greenhouse gas in less than three years that a key threshold for limiting global warming will be nearly unavoidable, according to a study released June 19.

The report predicts that society will have emitted enough carbon dioxide by early 2028 that crossing an important long-term temperature boundary will be more likely than not. The scientists calculate that by that point there will be enough of the heat-trapping gas in the atmosphere to create a 50-50 chance or greater that the world will be locked in to 1.5 degrees Celsius (2.7 degrees Fahrenheit) of long-term warming since preindustrial times. That level of gas accumulation, which comes from the burning of fuels like gasoline, oil and coal, is sooner than the same group of 60 international scientists calculated in a study last year.

“Things aren’t just getting worse. They’re getting worse faster,” said study co-author Zeke Hausfather of the tech firm Stripe and the climate monitoring group Berkeley Earth. “We’re actively moving in the wrong direction in a critical period of time that we would need to meet our most ambitious climate goals. Some reports, there’s a silver lining. I don’t think there really is one in this one.”

That 1.5 goal, first set in the 2015 Paris agreement, has been a cornerstone of international efforts to curb worsening climate change. Scientists say crossing that limit would mean worse heat waves and droughts, bigger storms and sea-level rise that could imperil small island nations. Over the last 150 years, scientists have established a direct correlation between the release of certain levels of carbon dioxide, along with other greenhouse gases like methane, and specific increases in global temperatures.

In Thursday's Indicators of Global Climate Change report, researchers calculated that society can spew only 143 billion more tons (130 billion metric tons) of carbon dioxide before the 1.5 limit becomes technically inevitable. The world is producing 46 billion tons (42 billion metric tons) a year, so that inevitability should hit around February 2028 because the report is measured from the start of this year, the scientists wrote. The world now stands at about 1.24 degrees Celsius (2.23 degrees Fahrenheit) of long-term warming since preindustrial times, the report said.

Earth's energy imbalance

The report, which was published in the journal Earth System Science Data, shows that the rate of human-caused warming per decade has increased to nearly half a degree (0.27 degrees Celsius) per decade, Hausfather said. And the imbalance between the heat Earth absorbs from the sun and the amount it radiates out to space, a key climate change signal, is accelerating, the report said.

“It's quite a depressing picture unfortunately, where if you look across the indicators, we find that records are really being broken everywhere,” said lead author Piers Forster, director of the Priestley Centre for Climate Futures at the University of Leeds in England. “I can't conceive of a situation where we can really avoid passing 1.5 degrees of very long-term temperature change.”

The increase in emissions from fossil-fuel burning is the main driver. But reduced particle pollution, which includes soot and smog, is another factor because those particles had a cooling effect that masked even more warming from appearing, scientists said. Changes in clouds also factor in. That all shows up in Earth’s energy imbalance, which is now 25% higher than it was just a decade or so ago, Forster said.

Earth’s energy imbalance “is the most important measure of the amount of heat being trapped in the system,” Hausfather said.

Earth keeps absorbing more and more heat than it releases. “It is very clearly accelerating. It’s worrisome,” he said.

Crossing the temperature limit

The planet temporarily passed the key 1.5 limit last year. The world hit 1.52 degrees Celsius (2.74 degrees Fahrenheit) of warming since preindustrial times for an entire year in 2024, but the Paris threshold is meant to be measured over a longer period, usually considered 20 years. Still, the globe could reach that long-term threshold in the next few years even if individual years haven't consistently hit that mark, because of how the Earth's carbon cycle works.

That 1.5 is “a clear limit, a political limit for which countries have decided that beyond which the impact of climate change would be unacceptable to their societies,” said study co-author Joeri Rogelj, a climate scientist at Imperial College London.

The mark is so important because once it is crossed, many small island nations could eventually disappear because of sea level rise, and scientific evidence shows that the impacts become particularly extreme beyond that level, especially hurting poor and vulnerable populations, he said. He added that efforts to curb emissions and the impacts of climate change must continue even if the 1.5 degree threshold is exceeded.

Crossing the threshold "means increasingly more frequent and severe climate extremes of the type we are now seeing all too often in the U.S. and around the world — unprecedented heat waves, extreme hot drought, extreme rainfall events, and bigger storms,” said University of Michigan environment school dean Jonathan Overpeck, who wasn't part of the study.

Andrew Dessler, a Texas A&M University climate scientist who wasn't part of the study, said the 1.5 goal was aspirational and not realistic, so people shouldn’t focus on that particular threshold.

“Missing it does not mean the end of the world,” Dessler said in an email, though he agreed that “each tenth of a degree of warming will bring increasingly worse impacts.”