Tuesday, May 19, 2026
Stephen Leahy
- Warmer, wetter and stormier – the largest ever scientific review of climate change will say there is virtually no doubt that emissions from burning fossil fuels are causing the documented rise in global temperatures.
Average temperatures are set to rise between two and 4.5 degrees C sometime between 2030 and 2050, bringing with them massive ecological impacts, according to media reports of leaked documents from the Intergovernmental Panel on Climate Change (IPCC), an umbrella organisation of scientists from around the world and the preeminent authority on climate change.
Part one of the IPCC’s massive Fourth Assessment Report will be officially made public in Paris on Feb. 2.
“It’s the same message that the IPCC has been saying for 20 years but with much better scientific understanding and certainty,” said Andrew Weaver, a climatologist at the School of Earth and Ocean Sciences in University of Victoria, Canada.
“The bottom line is that the temperature rise is not going to be any lower than two degrees C,” Weaver, one of the lead authors of the forthcoming IPCC report, told IPS.
Nearly 30 years ago, climate scientists began to calculate the impacts of the burning of fossil fuels on global temperatures. If the amount of carbon dioxide (CO2) in the atmosphere doubled from the pre-industrial average of 280 parts per million (ppm), it would raise global temperatures from 1.5 to 4.5 degrees C, they found.
Six years of study and analysis by more than 2,500 scientists in more than 130 countries involved in the IPCC process will conclude that doubling CO2 will result in a global temperature rise on average of two and 4.5 degrees C. The temperature increase will not be evenly distributed, and temperatures in Arctic regions will go much higher – four to eight degrees C.
The bottom end of the range is virtually guaranteed, but the upper could go much higher depending on complex, and poorly understood, positive feedback mechanisms.
A meltdown of the Northern hemisphere’s permafrost or a massive die-out of the Amazon rainforest, as projected in some models, could push global temperatures well above this range.
“This is not good news,” Weaver said with considerable understatement.
A two-degree C rise – unprecedented since the age of the dinosaurs – is hardly good news either.
“At two degrees C we will experience massive changes to the Earth’s ecosystems,” he said.
Heat waves and droughts will be more intense and last longer, while floods will be more frequent and more damaging. The rate of change will be too fast for most species to adapt, Weaver says.
While human societies in rich countries may be able to buffer themselves from most of the worst impacts, the world’s poor will not have that luxury.
“There will be massive displacements of people which will create major instability in the world,” said Weaver.
At 2.7 degrees C, the entire Greenland ice sheet will melt, eventually raising sea levels six to seven metres worldwide, he said.
The IPCC estimation of the impacts of climate change will be released in part two of the Fourth Assessment Report in early April. Part three will look at how to mitigate climate change and will be released in early May.
“The only real scientific question regarding climate change over the past two decades has been how bad and how fast,” said Naomi Oreskes, a professor of history and science studies, at University of California, San Diego.
“The only remaining issue is whether we will take appropriate action, soon enough,” Oreskes said in a press conference.
The IPCC process has become the “gold standard” for global scientific collaboration and has been copied by others, she says.
The IPCC operates under the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP) and does not fund any research itself. It collects, evaluates and synthesises scientific data. Any U.N. country can be a member of the IPCC and can challenge the findings in its reports. And consensus is required for every word in the “Summary for Policy Makers” section included in each report.
It’s an inherently conservative process, with oil-rich countries like Kuwait and Saudi Arabia always trying to tone down the conclusions and emphasise uncertainties and unknowns, said Weaver.
In other words, the IPCC report will be sober, factual and as un-dramatic as possible. However, it will conclude that the scientific evidence on human-induced climate change is overwhelming.
“It is time for the climate scientists to step aside and let the engineers of the world begin to develop solutions,” Weaver said.
Major new technologies and changes are going to be needed and quickly to prevent a doubling of CO2.
Many experts believe it is ironic that in era of rapid scientific development, cars and trucks still use an internal combustion engine developed 100 years ago and much of the world’s electricity comes from coal-fired power plants first developed in the 17th century.
“Only switching to energy-saving light bulbs is not going to cut it,” Weaver concluded.
An international treaty does exist to reduce the carbon dioxide emissions that contribute to global warming. Under the Kyoto Protocol, 36 highly industrialised nations must reduce their greenhouse gas emissions by at least 5.2 percent below 1990 levels by 2012. Parties have agreed that even tougher actions will be needed after that deadline, but many are already having trouble meeting the 2012 targets.
And the George W. Bush administration has rejected the treaty as too costly to enforce, even though the United States is by far the biggest emitter of greenhouse gases and consumes a quarter of global energy resources.