Climate change: What the new IPCC Sixth Assessment Report says about global warming

The report has found that climate change led to higher vector- and water-borne diseases, such as dengue, especially in Asia’s sub-tropical regions.

polar ice caps
The Assessment Reports, the first of which was in 1990, are the most comprehensive evaluations of the Earth’s climate. (File)

The latest Intergovernmental Panel on Climate Change (IPCC) report released on Monday has warned of several climate change-induced disasters over the next two decades even if strong action is taken to reduce greenhouse gas emissions.

The IPCC said humans and natural systems’ ability to cope with climate change was already being tested, adding that further rise in global warming would make it more difficult to adapt.

It noted that over 3.5 billion people or more than 45% of the global population were living in areas that were highly vulnerable to climate change. Identifying India as a vulnerable hotspot, it noted that several regions and important cities faced very high risk of climate disasters, including sea-level rise, flooding, and heatwaves.


The latest warnings from the second part of the IPCC’s Sixth Assessment Report talks about the impact of climate change, vulnerabilities and risks, and adaptation options. The first part, centred around climate change’ scientific basis, was released last August. The third instalment, set to come out in April, will look into the possibilities of reducing emissions.

The Assessment Reports, the first of which was in 1990, are the most comprehensive evaluations of the Earth’s climate. Hundreds of experts go through every piece of relevant and published scientific information available to prepare a common understanding of climate change. The four subsequent reports came out in 1995, 2001, 2007, and 2015. These are the basis of the global response on climate change.


The Sixth Assessment Report does says nothing remarkably new. Over the years, each report has built on the work of the previous reports, adding more information, evidence, and data, so that the conclusions have far greater certainty, clarity, and wealth of new evidence.

Each report has progressively expanded the scope of assessment and introduced fresh information about the different aspects of climate change.

For the first time, the latest report has assessed climate change’s regional and sectoral impacts. It has included vulnerabilities of, and risks to, mega-cities across the world. It has warned that Mumbai was at high risk of a sea-level rise and flooding, while Ahmedabad faced a serious heatwave danger.

Also Read | Climate change: Mumbai at high flood risk; Heat, humidity to make India uninhabitable if emissions not cut

Such granular information was not available in earlier reports. Flooding in Mumbai and heatwaves in Ahmedabad are common. What this report has done is looked at the granular data affecting these events and quantified the risks for clearer understanding of the threats these cities faced.

Also for the first time, the report has looked at its health impacts. It has found that climate change led to higher vector- and water-borne diseases such as dengue or malaria, especially in Asia’s sub-tropical regions. The report has also said deaths related to respiratory, circulatory, diabetic, and infectious diseases, and infant mortality are likely to go up with a rise in temperature. Increasing frequency of extreme weather events such as flooding and drought, heatwaves, and even air pollution was a contributing factor to allergic diseases, under-nutrition, and even mental disorders.


The report said climate change’s impacts were far greater, more frequent, and vastly more disruptive than previously estimated.

Based on increased observations and an improved understanding of the processes, the IPCC has understood the extent and magnitude of the impact of climate change on nature were greater than assessed previously. The impacts seen today are also appearing much faster, are more disruptive and widespread than expected 20 years ago.

The report added that while strong steps to reduce greenhouse gas emissions in the near term (the next 20 years) would substantially reduce the threats and the projected damages, it would still not be enough to eliminate all. If the temperature rise crossed the 1.5°C threshold from pre-industrial times, many changes could be irreversible.

The need to adapt measures is important, the report has stressed. It has also recognised the progress made to adapt to the new situation but pointed out that it was nowhere close to what the required levels in most places. The IPCC said the gaps in adaptation were a consequence of a lack of funds and political commitment, apart from the absence of a sense of urgency and reliable information.

Pointing to “feasible and effective” adaptation options that could reduce the risks, the report said the effectiveness of these options decreased sharply with further temperature increases.

The report said adaptation was essential to reduce harm but it must go hand in hand with ambitious lowering of greenhouse gas emissions for it to be effective because the effectiveness of many adaptation options declined with increased warming.


The IPCC reports are the scientific basis on which states build their policy responses. On their own, these reports are not policy prescriptive — they do not tell governments what to do. They are meant to present factual situations with scientific evidence.

Yet, these reports can help formulate the action plans to contend with climate change. The latest report’s detailed nature, with respect to sectoral and regional impacts, presents intelligence that can be acted upon, especially in countries that lack the capacity or the resources to make their own assessments. These findings are the product of the combined understanding of the largest group climate science of experts, lending it a credibility greater than individual studies.

These reports are also the basis for international climate change negotiations that decide the global responses. These negotiations have produced the Paris Agreement and the earlier Kyoto Protocol. The Paris Agreement, on the basis of the Fifth Assessment Report, seeks to contain the global temperature rise well below 2°C from pre-industrial times, while making efforts to limit it to 1.5°C.

The Sixth Assessment Report has presented lots of evidence to suggest that the 2°C-target could be disastrous and called for more ambition to keep the rise within 1.5°C.

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