Girls whose mothers took paracetamol (acetaminophen) during pregnancy had smaller ovaries at three months old, on average, than those whose mothers didn鈥檛 take the drug, according to a study of about 300 infant girls in Denmark. Infant boys whose mothers took paracetamol had smaller testes on average too, the study found.

That doesn鈥檛 prove paracetamol caused the reduction in the average size of ovaries and testes, though 鈥� this association could be a result of the conditions that led to the women taking paracetamol during pregnancy, or even due to chance alone. Nor is it clear whether having smaller ovaries or testes as an infant affects fertility in adulthood. However, the findings are in line with separate studies done in rats and mice, in isolated human ovaries and in human embryonic cells.

鈥淲e still recommend that pregnant women should use paracetamol with high fever or strong pain,鈥� says at Copenhagen University Hospital鈥揜igshospitalet. Not doing so can be risky, she says.

But most of the women in the study used paracetamol for headaches or musculoskeletal pain, rather than fevers, and could have managed their pain or discomfort in other ways, such as via rest, heat treatment or physiotherapy, says Fischer.

鈥淲e should have a dialogue about when paracetamol is actually necessary,鈥� she says. 鈥淚t is still a drug and it does have side effects. Maybe it shouldn鈥檛 be the first thing that we grab when we have discomfort.鈥�

The issue is that there are almost no safe drug-based alternatives to paracetamol for pregnant women. Most other painkillers aren鈥檛 recommended because they can cause congenital conditions.

Fischer鈥檚 team recruited 685 pregnant women during their first trimester, who were asked about their use of medicines every two weeks. They had an fetal ultrasound during their third trimester, and 302 daughters were examined around three months after birth.

Those exposed to paracetamol as a fetus had, on average, 40 per cent smaller ovaries by volume, 13 per cent smaller uteruses by volume and 23 per cent fewer ovarian follicles 鈥� the sacs that nurture immature eggs 鈥� compared with those who weren鈥檛 exposed. Higher doses were associated with a bigger effect, says Fischer, but no women took more than the recommended daily maximum of 4000 milligrams.

From autism to migraines, birth order may have wide-reaching effects

A study of more than 10 million siblings suggests that firstborns are more likely to be autistic and have allergies, while conditions like migraine and shingles tend to affect their younger sibling

The researchers also analysed data from another study on 1210 girls born in Copenhagen between 1997 and 2002, and found a link between fetal exposure to paracetamol and smaller ovaries during adolescence.

In animal studies, such effects led to reduced fertility and earlier reproductive ageing, but it isn鈥檛 clear whether this applies to people. 鈥淲e cannot say anything about the reproductive consequences for these girls,鈥� says Fischer. That will require long-term follow-up, which is hard to do.

The team also examined the boys who were born to the 685 women. 鈥淲e do see a difference, on average, in the boys as well,鈥� says Fischer. 鈥淸They] have a reduced testicular volume.鈥�

Animal studies suggest this could affect fertility in adulthood, but again it is still unclear if this will be the case for the boys. 鈥淲e can鈥檛 say anything about that because our cohort does not follow them that long,鈥� she says.

A paper describing the findings in girls was published today. A separate paper describing the findings in boys has been accepted by the same journal, but not yet published, says Fischer.

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鈥淚t is still too early to sound the alarm, and to remove this tool from the therapeutic arsenal for treating pain and fever,鈥� says at the National Institute of Health and Medical Research in France, who, in 2022, co-authored research showing that .

But this latest study, along with one from last year showing that paracetamol , suggest that the precautionary principle should be applied, especially during the first trimester, says Mazaud-Guittot.

鈥淩aising awareness of alternative, non-pharmacological methods should help to encourage a reduction in the use of medication for the treatment of various mild pains,鈥� she says.

鈥淭his paper would not change my practice or advice,鈥� says at University College London. The team carried out a number of different statical analyses, he says, and the more of these you do, the greater the odds of getting a statistically significant association by chance.

鈥淚 do agree that we cannot exclude the possibility of chance findings,鈥� says Fischer. 鈥淸But] adjusting for multiple testing could mean that we fail to detect a real effect.鈥�

Childbirth for many primate species is even harder than for humans

For decades, we鈥檝e thought that childbirth is uniquely challenging for humans, but it turns out that many other primates find the birth process just as difficult

Another issue is that people taking these medications could be sicker, including with one of the many infections that affect fetal development. They might also eat and behave differently, or vary genetically, says at the University of Pennsylvania. The team tried to take account of such confounding factors, but couldn鈥檛 completely rule them out.

鈥淚 would not jump to the conclusion that the statistical association observed is a causal association,鈥� says Lee. He thinks there should be further studies into this, but establishing a causal link, if there is one, won鈥檛 be easy. A trial in which women were randomly assigned to take paracetamol or not would be the best way, but this would be unethical in pregnant women, says Fischer.

There have been claims that taking paracetamol during pregnancy increases the risk of autism, but the evidence suggests otherwise. 鈥淭his in no way changes the conclusion that paracetamol is not linked to autism, as multiple studies featuring millions of pregnancies across Sweden, Denmark, Norway, Hong Kong, Taiwan and Japan have shown,鈥� says Lee.

The world is likely to overshoot 1.5掳C of warming within the next few years, a by the UN Environment Programme (UNEP) acknowledges. However, it says it is still possible to cool the planet back down to this level by the end of the century. Can it really be done? It isn鈥檛 impossible, but it certainly isn鈥檛 the most likely outcome.

The goal of limiting the increase in the average global surface temperature to 1.5掳C above pre-industrial levels looked implausible even back in 2015, when it was adopted as part of the Paris Agreement. The UNEP report can be seen as an 鈥渙fficial鈥� acknowledgment of what many have been saying for years: that it is now certain that we are going to blast right past this limit.

But some aren鈥檛 giving up on the target. There are no good outcomes if we remain above 1.5掳C, says at UNEP. 鈥淓ven if we exceed 1.5, let鈥檚 be very clear: that 1.5 target is still the goal. But now we need to approach it differently, from above.鈥�

Much of the report looks at the consequences of overshooting 1.5掳C and the need for adaptation to cope with the severe impacts this will bring. 鈥淲e will see increased food insecurity, increased water insecurity, impacts on human health 鈥� physical and mental 鈥� danger to our homes and our infrastructure,鈥� says at the University of KwaZulu-Natal in South Africa, one of the authors of the report. 鈥淭his will lead to the loss of livelihoods and certainly lives.鈥�

The world isn鈥檛 prepared for overshooting 1.5掳C, she says. 鈥淭herefore we have to advance our adaptation and development strategies to deal with those higher levels of warming, the greater range of risks and impacts鈥� Adaptation needs to be transformational to allow us to plan for a changing world.鈥�

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There will be no going back to how things were, says Roberts. 鈥淪ome losses will be irreversible, which means returning to 1.5 doesn鈥檛 mean we return back to the same world we left.鈥�

But what exactly should we be preparing for? The report focuses on a scenario in which rapid emissions cuts and massive-scale removal of carbon dioxide from the atmosphere result in a return to 1.5掳C of warming by the end of the century.

But achieving this would require limiting temperature rises to no more than 1.8掳C, says Roberts. Beyond this, there will be cascading effects from all the irreversible changes that make it much harder.

However, restricting warming to this level requires a halving of global emissions by 2035, says report author at Imperial College London. That seems highly unlikely given that emissions are still rising worldwide.

In addition to emissions cuts, the scenario envisaged in the report also requires carbon removal on a truly gigantic scale 鈥� enough not just to balance out hard-to-tackle emission sources, such as farming, and achieve net zero, but to go well beyond that to remove around 10 gigatonnes of CO2 each year. That compares with current emissions of around 40 gigatonnes.

This means scaling up carbon removal by a factor of around 100,000, says at ETH Zurich in Switzerland, who wasn鈥檛 involved in the report. Cheap forms of carbon removal, such as planting forests, can鈥檛 be scaled up this much because there isn鈥檛 enough land. Direct air capture could be scaled up, but it is really expensive, he says.

Knutti thinks achieving this is technically and financially possible, but not politically plausible. 鈥淲e should be honest when we talk to policy-makers and the public that this is not the thing to plan for,鈥� he says. 鈥淚 think the plan should be to adapt for at least 2 degrees, if not more.鈥�

at the University of Exeter in the UK is even less optimistic. 鈥淭here are still no credible plans for large-scale carbon dioxide removal,鈥� he says. 鈥淗uman societies must adapt and prepare for a warmer and more dangerous world that will persist potentially for centuries.鈥�

, also at ETH Zurich, points out that among , only two imply a return to 1.5掳C before 2150. The scenario based on current policies suggests warming of around 3掳C by 2100.

Until recently, overshooting and returning to 1.5掳C was no more than a scientific thought experiment, says at the German Institute for International and Security Affairs. Now it could become the 鈥渙fficial鈥� plan B for 1.5掳C. 鈥淭he overshoot concept may turn out to be no more than a way to mask ongoing failure,鈥� he says.

But even if getting the temperature back down to 1.5掳C isn鈥檛 likely, we have to try, says Weber. 鈥淲e have to give it a shot. There鈥檚 no real alternative.鈥�

鈥淣ow is the time to double down on climate action, not to give up on it,鈥� says Andersen. 鈥淓very fraction of a degree avoided, every year by which overshoot is shortened and every adaptation action taken will save lives, protect ecosystems and reduce economic losses.鈥�

The full extent of the deaths and damage caused by the enormous flash flood that swept down a river valley in Nepal and Tibet today won鈥檛 be clear for weeks. But initial analyses of satellite images and seismic data suggest that the collapse of a high glacier caused the disaster.

鈥淭here鈥檚 a glacier that rolls over a cliff at about 5200 metres,鈥� says at the University of Calgary in Canada. 鈥淚t鈥檚 just like a perfect straight line where it snapped off and dropped over a kilometre vertically to the valley bottom.鈥�

This collapse could be a result of global heating. 鈥淚t鈥檚 not that much of a stretch to think, yes, we鈥檙e seeing one terrible ramification of human-caused climate change,鈥� he says.

As the glacier flowed over the cliff and moved down the steep slope, deep crevasses would have formed in the ice. Warm weather in the past day or so may have melted a lot of snow and some glacier ice, with this liquid water weakening the glacier and causing the entire section flowing down the steep slope to collapse.

鈥淐omparing satellite imagery from yesterday and today, the glaciers in the vicinity do seem to have lost a fair bit of snow in the last 24 hours,鈥� says Shugar. 鈥淢y guess is that snow melt, and glacier ice melt as well, injected a lot of liquid water into the glacier, which percolated down to the bed and lubricated it. That was enough for it to collapse.鈥�

The potential energy released as heat when millions of tonnes of ice fell a kilometre may have melted large quantities of it, producing enough liquid water to generate the huge flash flood.

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鈥淢aybe the glacier breaking is only part of the story and there鈥檚 something else that we can鈥檛 see yet,鈥� says Shugar. 鈥淏ut as of now, that鈥檚 what it looks like.鈥�

The melting of ice due to the release of potential energy caused the Chamoli flash flood in India in February 2021. 鈥淚n that case, it was a large landslide but with a bit of glacier ice on top of it,鈥� says Shugar. 鈥淲hen that much ice falls, there鈥檚 a lot of heat generated and it can melt.鈥�

This event, however, was much larger. 鈥淭hese videos that we鈥檙e seeing are off the charts. This is horrific,鈥� he says. 鈥淚t looks like this will rank very high on the list of historic mountain disasters in terms of people killed, and cost.鈥�

The race to understand how and when Thwaites glacier will collapse

The loss of Antarctica鈥檚 doomsday glacier would transform our planet. Now scientists are revealing the secrets of this remotest of places, and asking the question: is its demise inevitable?

Some reports have suggested that an earthquake triggered the event, but this isn鈥檛 the case, says at the University of Grenoble Alpes in France. 鈥淚 have looked at the data from a few stations in the region, including a station from the Nepali national seismic network near Kathmandu, and we see the event very clearly in this record.鈥�

The record begins with a strong signal of a form typically associated with the mass movement of material, rather than with an earthquake, says Cook.聽鈥淭hen we see a long seismic signal typical of a large debris flow that lasts for hours.鈥�

The initially described the seismic event as an earthquake, but now says further analysis shows it was a landslide.

The signal is similar to one observed during the 2021 Chamoli event, says Cook.

Global heating may have and to the collapse of a glacier above the village of Blatten in Switzerland in 2025. Steep glaciers can break for reasons unrelated to climate change, says Shugar, but an increase in the frequency of this kind of disaster points to warming as a contributing factor.

鈥淢ountain communities around the world, from the Alps to the Andes and the Himalayas, are threatened by increasing intensity and frequency of mountain-related hazards,鈥� said , head of the United Nations Office for Disaster Risk Reduction,. 鈥淭heir lives, ways of life, culture, and heritage are all threatened.鈥�

鈥淭he El Ni帽o has blossomed. It is off the charts. Usual measures of El Ni帽o have blown past prior record levels in the period with good data, even though maximum effects are still several months in the future.鈥�

So writes renowned climate scientist James Hansen at Columbia University in New York in .

There are different ways of measuring El Ni帽os, which occur when warm surface waters spread eastwards along the equator across the surface of the tropical Pacific Ocean. Hansen thinks the best measure is how much warmer than usual the upper 300 metres of the eastern tropical Pacific becomes.

鈥淥ur preferred metric, the heat anomaly in the upper 300 meters of the Equatorial Pacific Ocean鈥� already exceeds the 1997-98 super El Ni帽o,鈥� he writes.

A more common measure, called the Ni帽o3.4 index, is based on how much warmer than usual the sea surface temperature is in the Pacific in the long rectangle between 5 degrees north and south of the equator, and between 120 and 170 degrees west.

鈥淭he more common Ni帽o3.4 metric, sea surface temperature鈥� in the equatorial Pacific, also far exceeds prior values,鈥� Hansen writes.

But at the Met Office, the UK鈥檚 national weather service, says the Ni帽o3.4 index has not yet exceeded previous super El Ni帽os. 鈥淭he anomaly in Ni帽o3.4 is currently about 2 degrees above the norm which is very high for this time of year but not quite as high as the anomaly at the peak of the 1997/1998 El Ni帽o which was around 2.5 degrees,鈥� Scaife told New 女生小视频.

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The disagreement on the Ni帽o3.4 index might partly be because this index is usually expressed . By contrast, the daily Ni帽o3.4 value before dropping back slightly.

鈥淚n this case, I would agree with Jim,鈥� says at the California Institute for Water Resources. 鈥淣i帽o3.4 values are clearly now the highest on record for the time of year, and are expected to remain so for the rest of the calendar year.鈥�

Using a running mean with a long lag is misleading in a rapidly evolving situation like this, says Swain.

However, during November 2015 the daily Ni帽o3.4 reached nearly 3.1掳C, so the current event is not yet as strong as the 2015 one on this measure, either. It appears Hansen meant to say the Ni帽o3.4 index exceeds values for this time of year, as Swain says. New 女生小视频 has asked Hansen for clarification, but had no response at the time of publication.

鈥淯nder the standard El Ni帽o metric region it鈥檚 still currently the third strongest event on record,鈥� says at Berkeley Earth. 鈥淏ut upper 300m heat is generally a leading indicator of what we will see at the surface.鈥�

鈥淚 agree that this El Nino is the biggest on record,鈥� says at the National Center of Atmospheric Research.

What鈥檚 clear is that this developing super El Ni帽o will soon exceed previous events on all measures. 鈥淚 have never seen an El Ni帽o signal this intense in our forecasts,鈥� Scaife said in . 鈥淚f the forecast is accurate鈥� then 2026 will far exceed our recent experience of El Ni帽o and its worldwide climate influences.鈥�

While Hansen is comparing the developing super El Ni帽o to other modern events for which we have direct temperature records, at Newcastle University in the UK thinks it could also exceed historical events suspected to be even larger.

鈥淭he super El Ni帽o evolving in the Pacific will likely be the biggest ever recorded, reaching or exceeding the levels of the 1877-1878 El Ni帽o which caused widespread impacts, including famines and around 50 million deaths (3-4 percent of the global population at the time), mostly across Asia and South America,鈥� Fowler said in a statement.

Every cancer is different. Because of that, researchers have for decades been working on personalised cancer vaccines designed to make the immune system recognise and attack cancers specific to each individual. The results have been mixed, but now a personalised cancer vaccine has produced positive results in a final-stage trial for the first time.

that people who had undergone surgery to remove severe skin cancers, called melanomas, survived longer without the cancer returning or spreading to other parts of the body if they were given a personalised mRNA cancer vaccine in conjunction with another immunotherapy, compared with receiving that immunotherapy alone.

The hope is that this personalised vaccine will work for many other types of cancer. Trials are already underway for . The other big mRNA company, BioNTech, is also testing personalised cancer vaccines in human trials.

What is a cancer vaccine?

Cancers are caused by cells accumulating mutations to the point where they go rogue and start multiplying out of control. Mutations in proteins that protrude from the surface of cells also make cancer cells 鈥渓ook鈥� a bit different to other cells. This allows our immune system to recognise and kill off many cancers without us ever knowing about it. But some cancers slip through the net 鈥� the idea of cancer vaccines is to teach the immune system to recognise them.

How are these vaccines made?

In the case of the Moderna vaccine, called , a sample of a person鈥檚 cancer 鈥� a biopsy 鈥� is sequenced. It is then compared with their healthy blood cells to identify surface proteins on the cancerous cells that have distinctive mutations. Up to 34 are selected, and mRNAs coding for those proteins are made and put in the vaccine.

What happens next?

The cancer vaccine is injected into muscles, just like with the covid-19 mRNA vaccine. Cells in the muscles then temporarily produce the cancer proteins, triggering an immune response to them.

Why use mRNA vaccine technology?

It is possible to use other kinds of vaccines, but mRNA has two huge advantages: speed and cost. Making protein-based vaccines requires using living cells, which is time-consuming and requires many safety checks. For people with cancer, the faster a vaccine can be created, the better.

Why the next generation of mRNA vaccines is set to be even better

mRNA vaccines are quick and easy to make, while virus-like nanoparticles produce a stronger immune response. Now, the two approaches are being combined to give us the best of both worlds

What immunotherapy was the vaccine combined with for the trial?

It is a so-called anti-PD-1 therapy consisting of an antibody called pembrolizumab (Keytruda). Many cancers evolve to evade immune attack by putting up a 鈥渄on鈥檛 attack me鈥� sign. Immune cells 鈥渞ead鈥� this sign with the help of a protein on their surface called PD-1.

Blocking PD-1 makes the 鈥渄on鈥檛 attack me鈥� sign invisible to immune cells, so they attack regardless. However, anti-PD-1 treatments work only if the immune system is already trying to attack a cancer, hence the advantage of combining them with a cancer vaccine to provoke that attack.

How well did the combined treatment work?

Moderna hasn鈥檛 told us yet. The company has announced only that the results of the phase III trial 鈥渄emonstrate statistically significant and clinically meaningful improvements鈥� in survival times.

The trial involved 1137 people who, after surgery to remove melanomas, were randomly assigned to get both the vaccine and pembrolizumab, or just pembrolizumab. What we do know is that in an earlier trial involving 157 people with melanoma over five years, the combination of the vaccine and pembrolizumab cut the risk of recurrence by 50 per cent and the risk of spread to other parts of the body by 60 per cent, compared with pembrolizumab alone.

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When will this treatment become available?

Analysts speaking to the say it could be approved next year. But because it is an individualised treatment, scaling up production will be much more complex than with a standard vaccine.

It also isn鈥檛 clear yet what the pricing will be 鈥� even with the help of mRNA technology, it won鈥檛 be cheap. A suggested it would cost around $200,000 per treatment. No wonder Moderna鈥檚 share price is soaring.

Will this work for all cancers?

The hope is it will work for many cancers, but we will have to wait on more phase III trial results to be sure. That said, several other earlier-stage mRNA cancer vaccine trials have produced promising results. In fact, a study last year estimated that on the basis of these results, their potential health benefits could be worth around $75 billion a year in the US alone.

We may finally have a cure for many different autoimmune conditions

A revolutionary cancer treatment is now being applied to a wide range of autoimmune disorders. Columnist Michael Le Page finds it is proving to be even more effective than expected

Are there any approved cancer vaccines already?

Not like intismeran autogene. Some sources will tell you for treating cancer: Provenge, BCG and T-VEC.

But Provenge is a treatment that involves removing immune cells from a person鈥檚 body, exposing them to a prostate cancer protein, then replacing them. BCG is the tuberculosis vaccine, which just happens to help treat some bladder cancers for reasons we still don鈥檛 understand. And T-VEC is a live herpes simplex virus engineered to kill cancer cells.

So only one of the three is a conventional vaccine, and its anti-cancer action is completely incidental.

What about the HPV and hepatitis vaccines?

These vaccines prevent infections by viruses that can cause cancers, rather than targeting cancers directly, which is an even better approach. The HPV vaccine has proved incredibly effective at preventing cervical cancer, for instance.

Climate models projecting higher warming for a given level of carbon dioxide have been discounted as unrealistic, but a new way of assessing models suggests they are accurate.

鈥淔or a given emission trajectory, we expect warming to be 25 per cent higher,鈥� says at ETH Zurich in Switzerland.

The conclusion has enormous implications. For instance, a project called the currently projects that average global surface temperatures will rise by 2.6掳C above pre-industrial levels by 2100 if countries implement existing policies. Gyuleva鈥檚 team鈥檚 results suggest we are instead heading for 3.25掳C.

How much the world will warm depends on how much more CO2 we put into the atmosphere and how the planet responds to that CO2. Different climate models vary in how much warming they project for a given CO2 level. For instance, some models suggest that a doubling of CO2 will result in the average global surface temperature increasing by around 1.6掳C above pre-industrial levels in the short term. Others suggest it could be as high as 3掳C.

鈥淭he range is big, and it really matters,鈥� says Gyuleva. 鈥淪o the point is to find out which ones are right.鈥�

Previously, this was done by using climate models to simulate the recent past. The models are fed data on greenhouse emissions over the past century or so, and their projected climate response is compared with what actually happened.

For the last report by the Intergovernmental Panel on Climate Change, a lot of these models simulated more warming than had happened, so were discounted. Based on the remaining models, the panel鈥檚 last report concluded that a doubling of CO2 would result in between 1.2掳C and 2.4掳C of warming in the short term, with a best estimate of 1.8掳C.

But there is lots of variability in Earth鈥檚 climate. For instance, during the La Ni帽a climate pattern, cooler seawater from deeper down spreads across the ocean, resulting in cooler surface temperatures. So, Gyuleva and her colleagues have filtered the historical climate record to try to remove the effect of variability due to phenomena like La Ni帽a.

Their results suggest that natural variability limited temperature rises between 1981 and 2014 鈥� a period that includes the so-called global warming hiatus in the first decade of the 21st century. 鈥淚t鈥檚 really exactly this period 1981 to 2014, which was used in the previous papers, where you see the strongest bias down,鈥� she says. 鈥淚t was really bad luck.鈥�

Correcting for this bias alone leads to higher estimates of the warming expected from a doubling of CO2. But Gyuleva鈥檚 team also assessed models using a new approach. Instruments on several satellites have been measuring how much short-wave radiation from the sun enters the atmosphere, and how much long-wave radiation is emitted. The difference between how much heat energy enters the atmosphere and how much leaves is the most fundamental measure of global warming.

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So, how well models project the trends in incoming and outgoing radiation as the world warms can be seen as a better measure of their performance than their projections of surface temperatures. But because the satellite measurements required to do this only began in 2001, this kind of assessment has only recently become possible.

The team found the models that best match the observed trends in short-wave and long-wave radiation project much greater warming. Based on the models that perform best at both kinds of assessments, the team concludes that a doubling of CO2 will lead to a rise of between 1.9掳C and 2.6掳C, with a best estimate of 2.25掳C. 鈥淥ur results need to be confirmed by more evidence from different sources before we can be fully confident,鈥� says Gyuleva.

鈥淭his seems to be a sound approach,鈥� says at the University of Oslo in Norway.

鈥淚n my opinion, the filtering out of natural variability is a valuable step forward,鈥� says at Duke University in North Carolina, although he isn鈥檛 yet convinced that the short-wave and long-wave trends are a good way to assess models.

鈥淚 think it鈥檚 a plausible conclusion and a reasonable approach,鈥� says at the University of New South Wales in Sydney.

But the findings are based on climate models, and none of them reproduces the key phenomena very well, says Sherwood. 鈥淭o do a better job of this we really need better climate models. On the other hand, the steep temperature rises of the last few years are going to lead to higher estimated ranges regardless of method.鈥�

In climate jargon, what Gyuleva鈥檚 team has estimated is known as the transient climate response. It is just one of three types of climate sensitivity, which vary in terms of the timescales involved.

Coral reefs have fuelled severe global warming in Earth鈥檚 past

Over the past 250 million years, periods when coral reef growth has peaked have coincided with big rises in sea temperatures

In the decades after a doubling of CO2, various feedbacks will kick in that lead to further warming, such as the continued warming of the oceans. The response after these medium-term feedbacks have kicked in is known as the equilibrium climate sensitivity. Last year, it was shown that the trends in short-wave and long-wave radiation suggest the equilibrium climate sensitivity is higher than previous estimates.

There are also very slow feedbacks that take centuries or more, such as the melting of ice sheets. Estimates of this earth system sensitivity 鈥� the full response to a doubling of CO2 over many millennia 鈥� are as high as 7掳C.

However, if atmospheric CO2 levels were lowered by carbon removal, some of the longer-term consequences would be avoided.