The Climate Crisis is accelerating and all the main players predict that the world will warm by more than the 1.5C Paris Agreement target by next year. They also predict that the average global temperatures will also broach the Paris maximum of 2C by 2036 or 2039 at the very latest, according to statistician Grant Foster and Stefan Rahmstorf, a German oceanographer and climatologist.

The researchers tabulated the best guess estimates of the leading institutions studying climate change, forecasting when the various temperate levels will be reached.

“The most important insight from these adjusted data is that there is no longer any doubt regarding a recent increase in the warming rate. Although the world may not continue warming at such a fast pace [~0.43/dec], it could likewise continue accelerating to even faster rates,” well known climatologist Lee Simmons said in a social media post.

According to scientists, any temperature increase of more than 2C above the pre-industrial baseline will result in catastrophic and irreversible ecological damage. At increases of above 3C-4C sea levels will rise several metres, large parts of the globe will become uninhabitable, humanity’s food security will be threatened and large numbers of plant and animal species will become extinct.

 

Temperature rising threshold expectations, ending value in °C, rate in °C/decade
Data	value	rate	cross +1.5°C	cross +2.0°C	cross +2.5°C	cross +3.0°C	cross +3.5°C	cross +4.0°C
NASA	1.45	0.42	2026	2037	2049	2061	2073	2085
NOAA	1.45	0.42	2026	2037	2049	2061	2073	2085
HadCRU	1.42	0.39	2026	2039	2052	2065	2077	2090
Berkeley	1.45	0.43	2026	2037	2048	2060	2072	2083
ERA5	1.54	0.48	2024	2034	2044	2054	2065	2075
Average	1.46	0.43	2026	2037	2048	2060	2072	2084
Source: Grant Foster and Stefan Rahmstorf (2025 preprint)

The table paints a stark picture of the rapidly closing window for global climate action. Based on projections from six key temperature datasets – NASA, National Oceanic and Atmospheric Administration (NOAA), Hadley Centre/Climatic Research Unit (HadCRU), Berkeley Earth, European Centre for Medium-Range Weather Forecasts (ERA5), and a calculated average – global warming is not only accelerating but is also likely to breach critical temperature thresholds far sooner than previously expected. Scientists say the 1.5C-2C range has already been missed and temperatures are currently on track for a 2.7C-3.1C rise by 2050 as a best case scenario.

Notably, all these leading datasets project that the 1.5°C threshold will be crossed by 2026, with ERA5 – widely considered one of the most sensitive reanalysis datasets – forecasting that this milestone has already arrived last year, the first year when monthly temperatures were above the 1.5C every month of the year.

(The confusion is that the 1.5C Paris goal is supposed to exclude annual fluctuations caused by things like the El Niño effect and other variables, so nominal temperature increases are not necessarily the same as the adjusted temperature increases cited by the Paris Agreement.)

Nevertheless, there is no doubt that temperatures are continuing to rise and that the rate of the rise has accelerated and is growing faster than any of the models used in 2015 when the Paris accord was signed. The convergence amongst the predictions strongly reinforces the message from the Intergovernmental Panel on Climate Change (IPCC) that the 1.5°C limit is not a distant benchmark, but an imminent reality.

Beyond that, the projected timelines diverge slightly but all show the steady increase in temperatures towards catastrophic levels.

The 2°C mark is expected to be hit within just over a decade in 2037, with ERA5 again predicting an earlier breach in 2034. For the 3°C threshold, the average across all datasets is 2060, with ERA5 consistently forecasting earlier crossings than the rest – indicative of its higher estimated warming rate (0.48°C/decade compared to an average of 0.43°C/decade).

The further we go into the future, the wider the spread becomes. HadCRU consistently predicts later arrival of each threshold, estimating a breach of 4.0°C only by 2090, compared to 2084 on average and 2075 under the ERA5 model.

What is clear across all projections is the trajectory: without immediate and large-scale emissions cuts, the world is locked into a steep warming path. The fact that even conservative models now expect a 2°C breach within a little over a decade should serve as a wake-up call for policymakers. Every additional fraction of a degree will escalate climate impacts – raising sea levels, increasing the intensity of extreme weather events, and threatening food and water security across the globe.

Specifically, scientists best guess of what will happen as each of these thresholds are cross include:

At 2°C of global warming, the Earth crosses a threshold long described by scientists as “perilous.” Coral reefs, vital to marine biodiversity and coastal protection, are expected to all but vanish, with over 99% bleaching or dying. Heatwaves will become more frequent, longer and deadlier – posing direct threats even to healthy populations. Water shortages will intensify across regions such as South Asia and North Africa, with hundreds of millions forced to migrate to cooler climes. Global food security begins to fray, as yields of staple crops like wheat and maize fall in vulnerable regions and the rice crisis that has already appeared in Asia intensifying. Although northern Europe and some high-latitude zones may temporarily benefit, the global balance tilts towards growing insecurity, with economic impacts felt most severely in the Global South.

At 3°C of warming, the climate crisis escalates into a state of catastrophe. Entire ecosystems face collapse, including parts of the Amazon rainforest, which may flip from carbon sink to carbon source. Coastal cities experience chronic flooding as sea levels rise faster than adaptation efforts can keep up. Agricultural systems struggle under the combined pressure of heat, drought and erratic rainfall, with global grain supplies under sustained threat. Deadly heatwaves become an annual event, and wildfire activity triples across regions such as southern Europe, California and Australia. Human displacement increases dramatically, with food and water stress fuelling political instability and cross-border tensions.

At 4°C, the Earth enters an unfamiliar and extremely dangerous state. Major parts of the tropics and subtropics become effectively uninhabitable due to extreme heat and humidity. The northern permafrost will be almost completely gone and release up to 1,000 gigatonnes of primordial CO₂ into the atmosphere, potentially triggering runaway warming. Sea levels rise by several metres over time, threatening the survival of major coastal megacities. London and most of the capital of the west coast of Africa will be underwater. Agricultural systems in large parts of the world collapse, undermining global food trade and leading to widespread famine. Freshwater becomes scarce for over a billion people, and mass migration – possibly hundreds of millions – puts unprecedented pressure on borders and governments. The global economy shrinks, insurance systems fail and the foundations of international stability are placed at risk.