The first study of microplastics in Texas coastal sediment was funded through a local environmental activist’s landmark legal victory over plastic pollution, one of many such research projects.

By Dylan Baddour

A recent study found surprisingly low levels of harmful microplastics in the sediments of Texas bays that are notorious for plastic pollution. This led researchers from the University of Texas at Austin to conclude the microplastics were being swept out to sea.

Microplastics from Texas Bays Are Washed Out to Sea, New Study Says

Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.

This week

US budget bill ‘would kill IRA’

WAYS AND MEANS: The future of Joe Biden’s signature climate policy, the Inflation Reduction Act (IRA), is in doubt after Republicans on two key Congressional committees passed budget proposals that “would effectively kill” it, reported Heatmap News. The proposals would end clean-energy tax credits and rebates for electric vehicle (EV) purchases, “claw back” climate grants and “slash” related spending, said Reuters.

DEFENCE DOUBTS: While a “small subset” of House Republicans have been trying to defend the IRA, it is unclear if they would block passage of the wider budget bill to get their way, according to E&E News. In the Senate, Politico said “some” Republicans are “pushing back” on the current proposals. A New York Times feature said Republican districts “have the most to lose” if all of the IRA tax credits are repealed. Semafor reported Republicans were “wrestling with possible failure” of the bill, in the face of opposition from Democrats and their own ranks. (Law firm Grant Thornton said policymakers were hoping to pass the bill by 4 July.)

SOCIAL COST: Meanwhile, a new White House memo directed US government agencies to disregard economic damages from climate change, reported E&E News. Under a headline asking, “What’s the cost of pollution? Trump says zero”, the New York Times explained that the “social cost of carbon” had been used for more than two decades to help weigh the costs and benefits of federal policies and regulations. It said the move could face legal challenges.

Around the world

• DOWNPOUR DEATHS: More than 100 people were killed by floods in the Democratic Republic of the Congo, Agence-France Presse reported. Extreme rainfall also killed at least seven people in Somalia, the Associated Press said.
• PARIS PERIL: A UK opposition minister falsely attacked climate science and said his party could exit the Paris Agreement if elected, the Guardian said. The Guardian also reported on how Australia’s new opposition leader “could abandon net-zero”.
• GERMAN GAS: New economy minister Katharina Reiche wants more gas-fired power plants, according to Die Zeit. The country’s climate council warned the new government’s plans could breach climate goals, said Clean Energy Wire.
• DENGUE DANGER: Colombia’s El Espectador reported on rising climate-driven risks from dengue fever in Brazil, Costa Rica, Ecuador, Mexico and Panama.
• COP30 CREW: The Brazilian COP30 presidency has appointed 30 envoys, including “key liaisons” for strategic regions such as China’s Xie Zhenhua, Jonathan Pershing from the US and former UNFCCC chief Patricia Espinosa, Climate Home News said.

60%

The yearly rise in EV sales in emerging markets in Asia and Latin America in 2024, according to new data from the International Energy Agency.

Latest climate research

• Even passing 1.5C of global warming temporarily would trigger a “significant” risk of Amazon forest “dieback”, said research covered by Carbon Brief.
• Rapidly rising emissions from China’s agricultural machinery could “hinder” the country’s push towards net-zero, according to a study covered by Carbon Brief.
• Findings in Environmental Research Letters found that the benefits of CO2 “fertilisation” on forests are likely to be constrained by warming.

(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)

Captured

For the first time on record, China’s CO2 emissions have fallen as a result of clean energy expansion rather than weak growth in electricity demand, according to new analysis for Carbon Brief. The analysis, which has been covered by outlets including AFP, Semafor and the New York Times, found that China’s emissions from fossil fuels and cement fell 1.6% in the first quarter of 2025 and are now 1% below the peak reached in March 2024. The months ahead will be critical for what comes next, as Beijing is working to finalise its next international climate pledge for 2035 and its five-year plan for 2026-2030.

Spotlight

How Poland started speeding away from coal power

This week, Carbon Brief reports on coal falling to barely half of Poland’s power supplies.

The first round of Poland’s presidential election is on Sunday and Rafał Trzaskowski, from prime minister Donald Tusk’s centre-right party Civic Platform, is favoured to win.

Long seen as one of the world’s most coal-reliant countries, Poland’s electricity system is in the midst of dramatic and increasingly rapid change.

When Poland joined the EU in 2004, coal-fired power stations supplied 93% of the country’s electricity. Coal accounted for more than three-quarters of the total as recently as 2018, the year the country hosted COP24 in Katowice.

Since then, a gradual shuffle away from coal has turned to a sprint.

In 2024, coal generated little more than half of Poland’s electricity, according to data from thinktank Ember – and a coal power phaseout by 2035 is now seen as a realistic prospect.

While the topic has not played a big role in the election campaign, there is now broad public acceptance that “coal is over in Poland”, said Joanna Maćkowiak-Pandera, president of Polish thinktank Forum Energii. She told Carbon Brief:

“The extreme rightwing tries to claim that coal is the future and there is coal for [another] 400 years…[But] even the coal-mining sector does not believe it.”

As of 2024, coal contributed just 53.5% of electricity generation in Poland, with wind and solar making up 23.5%, gas power 12.1% and other renewables another 6.3%.

Coal ‘death spiral’

The “death spiral” for coal power is due to the high cost of coal mining in Poland, the old age of coal power plants, pressure from climate policies such as the EU emissions trading system (EUETS) and a loss of market share to renewables, said Maćkowiak-Pandera:

“You can be pro-coal, but you will not change the economics, physics, geology and the reality of the financial market.”

Until 2023, the right-wing Law and Justice party (PiS) had held the reins of government, having won the 2015 election after promising to protect the coal industry.

Following power cuts that summer, however, PiS increasingly accepted that renewbles – particularly solar power – could support energy security, explained Maćkowiak-Pandera.

(Renewables enjoy broad public support and are associated with energy security, she said.)

With backing from government policy, Poland’s solar capacity leapt from just 200 megawatts in 2015 to more than 20 gigawatts in 2024 – a 100-fold increase.

Still, PiS strongly resisted calls to phase out coal. In 2020, it struck a deal with unions to subsidise the Polish coal-mining industry until 2049. The subsidies remain in place.

After winning parliamentary elections in 2023, Tusk promised a “much faster energy transition” based on renewables and nuclear power, said Maćkowiak-Pandera.

While utility firms would “really love” to phase out coal plants within as little as three to five years, there is a growing consensus around 2035 as a more achievable end date, she said:

“It’s really not controversial any more…I speak with politicians, with utilities, with [electricity] transmission system operators, even with miners. Everybody is aware of the situation.”

Instead, there is a practical conversation around how best to replace coal at the lowest cost, explained Maćkowiak-Pandera.

This will mean more renewables, but also the flexible capacity needed to manage the grid – including some new gas-fired power plants – as well as energy storage and market reforms, she said.

Poland’s rapid transition may not have made many headlines, but other major coal-burning countries are starting to pay attention.

Maćkowiak-Pandera has welcomed delegations from China, South Africa, Mexico and Brazil, eager to learn about Poland’s experience. She added:

“For Chinese partners, it’s interesting because they like [our] pragmatic approach…they like that Poland [is] sometimes not mentioning climate, [but] is doing it anyhow.”

Watch, read, listen

CHINESE CROWING: A widely shared blog post on nationalist media outlet Guancha said China was taking climate action to “win the future energy revolution” and, among other things, to “save at least $600bn” on imported oil by shifting to EVs.

‘RUNNING BLIND’: For the Bulletin of Atomic Scientists, climate scientist Peter Gleick said the Trump administration’s “purges” of climate research were “threats to national security”.
‘REALISM’ REJECTED: The Wicked Problems podcast discussed the “defeatism” behind a recent initiative calling for “climate realism”, as well as the “abundance agenda”.

Coming up

• 18 May: Poland presidential election
• 19 May: EU-UK summit, London
• 19-23 May: First UN climate week 2025, Panama City, Panama
• 19-27 May: World Health Assembly 2025, Geneva, Switzerland

Pick of the jobs

• European Commission, programme manager (climate change and sustainable energy) | Salary: Unknown. Location: Brussels, Belgium
• Dialogue Earth, southeast Asia editor | Salary: £43,370. Location: London
• Royal Botanic Gardens Kew, postdoctoral research associate in genomics and climate change | Salary: £43,751. Location: London

DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.

This is an online version of Carbon Brief’s weekly DeBriefed email newsletter. Subscribe for free here.

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The post DeBriefed 16 May 2025: Has China’s CO2 peaked?; US bill ‘would kill IRA’; Poland’s coal collapse appeared first on Carbon Brief.

DeBriefed 16 May 2025: Has China’s CO2 peaked?; US bill ‘would kill IRA’; Poland’s coal collapse

Even passing 1.5C of global warming temporarily would trigger a “significant” risk of Amazon forest “dieback”, says a new study.

Dieback would see large numbers of trees die, shifting the lush rainforest into a dry savannah.

The research, published in Nature Climate Change, assesses the impact of “overshooting” the aspirational goal of the Paris Agreement on the Amazon and Siberian forests.

Overshoot would see warming surpass 1.5C above pre-industrial levels in the coming decades, before being brought back down before 2100 through large-scale carbon dioxide removal.

Using hundreds of climate-model simulations, the authors assess the influence of the “sensitivity” of the climate – a measure of the planet’s temperature response to a given increase in atmospheric CO2.

Across all simulations where global warming in 2100 surpasses 1.5C, 37% show “some amount of dieback”, the study says.

However, the risk increases further in the long term, with “55% of simulations exhibiting dieback by 2300”.

One author tells Carbon Brief that the study highlights that overshooting 1.5C leaves forest ecosystems “exposed to more risk than [they] need to be”.

The findings show that “we can’t afford complacency”, he warns.

Warming pathways

As the planet warms, there is an increasing risk that parts of the Earth system will cross “tipping points” – critical thresholds that, if exceeded, could push a system into an entirely new state.

For example, a seminal 2022 study warned that five tipping elements – including the collapse of the West Antarctic ice sheet and abrupt permafrost thaw – are already within reach, while others are becoming increasingly more likely as temperatures rise.

One way to limit warming to 1.5C by the end of the century involves initially overshooting the threshold. However, research published last year warns that the longer the 1.5C threshold is breached – and the higher the peak temperature – the greater the risk of crossing tipping points.

The new study uses modelling to investigate the risks of overshoot for the Amazon and Siberian forests.

The paper considers three illustrative mitigation pathways taken from the Intergovernmental Panel on Climate Change’s (IPCC) mitigation report from its sixth assessment cycle, which was published in 2022.

Gregory Munday is an applied scientist at the UK Met Office Hadley Centre and lead author on the study. He tells Carbon brief that the authors selected “optimistic” pathways that “each have different relationships to the Paris Agreement goals”.

For each scenario, the authors assess a range of different climate sensitivities – a measure of the planet’s temperature response to a given increase in atmospheric CO2. The average outcome of each pathway is:

• The “renewables” scenario shows a future with reduced emissions and a heavy reliance on renewable energy, which keeps warming below 1.5C by 2100.
• The “negative emissions” pathway shows a world in which warming initially overshoots the 1.5C threshold, but extensive use of carbon removal sees warming drop back below 1.5C before 2100.
• The “gradual strengthening” pathway illustrates a strengthening of climate policies implemented in 2020, with rapid reductions mid-century and a reliance on net-negative emissions by the end of this century. This pathway sees global average temperatures reach 1.8C by 2100. 

The authors run the emissions pathways through a simple climate “emulator” model, which calculates the global temperatures associated with each emission pathway.

The charts below show cumulative CO2 emissions (left), atmospheric CO2 concentration (middle) and changes in global average surface temperature compared to the pre-industrial level (right), for the renewables (green), negative emissions (purple) and gradual strengthening (yellow) pathways until the year 2300.

The authors then use a different modelling framework to project the impacts of each emissions scenario.

Study author Dr Chris Jones leads the UK Met Office Hadley Centre’s research into vegetation and carbon cycle modelling and their interactions with climate. He tells Carbon Brief that the new study is the first application of this modelling framework, which he describes as a “rapid response tool”.

He says the tool was developed to “rapidly look at a range of climate outcomes, both global and local, for new scenarios”, adding that it provides a “pretty good approximation” of what traditional global climate models would do.

Munday adds that the framework is able to produce results within days or weeks, rather than taking “months and months”.

Finally, the authors use land surface model JULES to assess forest health under the different scenarios. Overall, the authors produce 918 simulations each of Amazon and Siberian forest health.

Forest health

The authors assess forest health using two metrics. The first is the forest growth metric “net primary productivity”, a measure of the rate that energy is stored as biomass by plants, which can indicate forest productivity. The second metric, forest cover, is a way of measuring the forest’s long-term response.

The models show that rising CO2 levels causes net primary productivity to increase, due to the CO2 fertilisation effect, driving more rapid forest growth. Conversely, many of the impacts of climate change, such as increased heat and changes to rainfall patterns, can be detrimental to forests, damaging or killing trees.

To identify the impacts of overshooting 1.5C on the Amazon and Siberian forests, the authors compare the “renewables” and “negative emissions” pathways. Both of these scenarios reach a similar global average temperature by the year 2100, but the former does so without overshoot, while the latter overshoots 1.5C before temperatures come back down.

The maps below show the difference in net primary productivity in the Amazon (left) and Siberian forests (right) between the two scenarios in the year 2100. Brown shading indicates that net primary productivity was higher in the non-overshoot scenario, while blue indicates that it was higher in the overshoot scenario.

The maps show that “large areas of both Amazonian and Siberian forest show reduced net primary productivity” by 2100 due to overshoot, compared to a scenario with no overshoot, the paper says.

‘High-risk zones’

From the three pathways, the authors generate 918 simulations of future climate and corresponding Amazon forest health.

The authors use these results to identify which future temperature and rainfall conditions result in net forest “dieback”. This is when large numbers of trees die, shifting the rainforest into a dry savannah.

The plots below show which simulations result in Amazon dieback by the year 2100 (left) and 2300 (right), for different amounts of rainfall and temperature levels in the year 2100. Each graph is divided into four sections – hot and wet (top right), hot and dry (bottom right), cold and wet (top right) and cold and dry (bottom right). These sections are based on average regional temperature and rainfall in the year 2100.

Coloured dots indicate scenarios that see forest dieback. These are coloured by pathway, for renewables (green), negative emissions (purple) and gradual strengthening (yellow). Grey dots indicate scenarios without Amazon dieback. The red lines indicate “high-risk climatic zones”, above which there is “a significant risk of dieback”.

The study finds that most Amazon dieback scenarios happen in hot, dry conditions, the authors note.

Across all simulations where warming in 2100 is above 1.5C, 37% show “some amount of dieback” the study says. However, in these model runs, the risk increases further in the long term, the study notes, with “55% of simulations exhibiting dieback by 2300”.

Prof Nico Wunderling is a professor of computational Earth system science at the Potsdam Institute for Climate Impact Research and was not involved in the new research. He tells Carbon Brief it is significant that, according to this study, the Amazon will face impacts from climate change below the tipping point threshold of 2-6C, as assessed in the landmark 2022 tipping points paper.

The authors also carry out this analysis for Siberian forests. Instead of a drop in tree cover, they find a change in the composition of trees. Munday tells Carbon Brief that the vegetation shifts “from grassy surface types to lots more trees and shrubs” in a process called “woody encroachment”.

Woody encroachment can have significant negative impacts on terrestrial carbon sequestration, the hydrological cycle and local biodiversity.

“The Siberian forest is probably committed to a long-term, and possibly substantial, expansion of tree cover,” the authors write.

High-risk scenarios

The greatest uncertainty in this study comes from the spread of climate sensitivities, Munday tells Carbon Brief.

He elaborates:

“This means that although we simulate the impacts from extremely optimistic mitigation scenarios, there is a chance that the Earth’s climate sensitivity is much higher than we expect, and so, small but significant risks of short- and long-term forest ecosystem impacts exist in spite of the choice of these strong-mitigation scenarios.”

In other words, if climate sensitivity is higher than expected, forests could face harmful impacts even under low emissions scenarios.

Dr David McKay – a lecturer in geography, climate change and society at the University of Sussex – is the lead author of the 2022 study. He tells Carbon Brief that the new paper “shows the value in focusing not just on model averages, but also exploring a wide range of possible futures to capture potential ‘low probability, high impact’ outcomes”. He adds:

“[The study shows] how negative emissions to reduce warming might help restabilise these forests in future if we do overshoot 1.5C, but as such large-scale CO2 removal remains hypothetical, we shouldn’t assume we can rely on this in practice.”

However, McKay also notes some uncertainties in the models used. Mckay tells Carbon Brief that the vegetation model used in this study doesn’t include fire and “has some limitations around soil moisture stress and vegetation in the tundra”. These are “likely important for resolving potential tipping points in these biomes”.

Therefore, he adds, the study “doesn’t show how regional tipping points could potentially further amplify and lock-in these future forest shifts, even with negative emissions”.

Dr David Lapola is researcher at the University of Campinas in Brazil and was not involved in the study. He also warns that vegetation models provide a “poor representation of how CO2 may affect these forests directly”. Lapola argues that scientists must “collect field data to make any new advancement with models”.

Nevertheless, Lapola tells Carbon Brief that studies such as this will be “extremely useful” for the IPCC’s upcoming seventh assessment cycle, which will include a dedicated chapter on tipping points and other “low-likelihood high impact events” for the first time.

Study author Jones tells Carbon Brief that overshooting 1.5C leaves forest ecosystems “exposed to more risk than [they] need to be”. The findings show that “we can’t afford complacency”, he warns.

Forests taking longer to recover from severe ‘megafires’ since 2010

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The post ‘Significant’ risk of Amazon forest dieback if global warming overshoots 1.5C appeared first on Carbon Brief.

‘Significant’ risk of Amazon forest dieback if global warming overshoots 1.5C