Climate change widespread, rapid, and intensifying

The first part of the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC) was released yesterday, 9 August. IPCC is the United Nations body for assessing the science related to climate changes and their report clearly shows that recent changes in the climate are widespread, rapid, and intensifying. Guðfinna Aðalgeirsdóttir, professor at Faculty of Earth Sciences at the University of Iceland is one of the lead authors of the report, she contributed to Chapter 9 on Ocean, Cryosphere and Sea Level change. This is the first time an Icelandic scientist is a lead author for an IPCC report, but Icelandic scientists have contributed to previous reports.

This report shows that it is indisputable that human activities are causing climate change and making extreme climate events more frequent and severe, causing continued mass loss of glaciers and consequent sea level rise. The report also shows that human actions still have the potential to determine the future course of climate. The evidence is clear that carbon dioxide (CO2) is the main driver of climate change, even as other greenhouse gases and air pollutants also affect the climate.

The IPCC states that scientists are observing changes in the Earth’s climate in every region and across the whole climate system, according to the report. Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion—such as continued sea level rise—are irreversible over hundreds to thousands of years.

However, strong and sustained reductions in emissions of carbon dioxide (CO2) and other greenhouse gases would limit climate change. While benefits for air quality would come quickly, it could take 20-30 years to see global temperatures stabilize.

But it is not just about temperature. Climate change is bringing multiple different changes in different regions – which will all increase with further warming. These include changes to wetness and dryness, to winds, snow and ice, coastal areas and oceans. This means:

• Climate change is intensifying the water cycle. This brings more intense rainfall and associated flooding, as well as more intense drought in many regions.
• Climate change is affecting rainfall patterns. In high latitudes, precipitation is likely to increase, while it is projected to decrease over large parts of the subtropics. Changes to monsoon precipitation are expected, which will vary by region.
• Coastal areas will see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion. Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century.
• Further warming will amplify permafrost thawing, and the loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of summer Arctic sea ice.
• Changes to the ocean, including warming, more frequent marine heatwaves, ocean acidification, and reduced oxygen levels have been clearly linked to human influence. These changes affect both ocean ecosystems and the people that rely on them, and they will continue throughout at least the rest of this century.
• For cities, some aspects of climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea level rise in coastal cities.

For the first time, the Sixth Assessment Report provides a more detailed regional assessment of climate change, including a focus on useful information that can inform risk assessment, adaptation, and other decision-making, and a new framework that helps translate physical changes in the climate – heat, cold, rain, drought, snow, wind, coastal flooding and more – into what they mean for society and ecosystems.

Further information can be found on the Intergovernmental Panel on Climate Change website.