Scientists today completed the world’s most comprehensive review of research into the science, causes, and impacts of climate change. It’s over 5,000 pages long, cites more than 31,000 pieces of research and has taken seven years to complete.
Here’s 10 charts that illustrate the Intergovernmental Panel on Climate Change’s (IPCC) fifth assessment report, from rising carbon dioxide emissions to transforming the energy sector.
What’s going on?
The first part of the IPCC’s report looks at how human activities affect the climate. It says scientists are more sure than ever – 95 per cent certain – that humans are causing extra warming.
1. Emissions are increasing
Since pre-industrial times, the amount of carbon dioxide in the atmosphere has increased 40 per cent, as this graph shows:
The biggest cause of the increase? Burning fossil fuels. Land use changes, such as turning forest into farmland, are the second biggest cause.
2: It’s getting warmer
What are the consequences of such as increase? Rising temperatures, for a start.
This graph shows how temperatures have changed since 1950, and how they’re expected to rise in the future:
The earth’s surface warmed by approximately 0.85 degrees between 1880 and 2012. Surface temperatures fluctuate substantially, and warming has occurred more slowly in some decades than others. But the IPCC’s data confirms a long-term warming trend.
If the world cuts emissions aggressively, temperatures may rise by only around one degree by the end of the century (the blue chunk of the graph above). But the IPCC says the world is likely to be 3.7 degrees warmer by 2100 if emissions continue to increase at the current rate (the red chunk).
3: Sea levels are rising
Sea levels are predicted to rise as glaciers and ice sheets melt, and oceans warm and expand. This graph shows how much the IPCC expects sea levels to rise, depending on future emissions:
By the end of the century, sea levels are likely to have risen by between 26 and 82 centimetres, the IPCC says.
If emissions drop sharply, the IPCC projects that sea levels may rise an average of 40 centimeters. If emissions continue to rapidly increase, sea levels could rise as much as 63 centimeters, on average.
4: Rainfall patterns are changing
Rising emissions will also affect how much rain there is in different parts of the world. This chart shows not everywhere will be affected in the same way.
The left map shows changes in rainfall if the world aggressively cuts emissions. The map on the right shows what could happen if emissions continue to rise apace. The greens and blues show areas expected to get wetter, while the yellows and oranges show areas that will get drier.
If the world significantly curbs emissions, the contrast between wetter and drier places will be less obvious.
But if emissions keep rising, some places could receive up to 50 per cent more rainfall between 2081 and 2100 than they did between 1986 and 2005. Others may experience 30 per cent less.
What’s going to happen?
The second part of the IPCC’s report focuses on the impacts of climate change. It finds climate change already contributing to problems like flooding, food supply disruption, and species migration and extinction.
5: Global impacts
The IPCC expects climate change to impact every corner of the globe, in some way. This map shows which places will experience the various impacts of climate change:
Each symbol on the map represents a different impact – from glacier melt to increased wildfires. If the symbols are filled in, it means scientists think climate change is a big contributor to the problem. If the symbols are empty, it means researchers expect climate change to have a minor effect.
As you can see, the IPCC expects climate change to have a major impact on glaciers, snow and ice in all regions (excluding small islands). It’s also expected to have a major effect on rivers, lakes, floods, and drought in Europe, North America, Asia, Africa and the Arctic.
6: Risks to human health
Climate change is also expected to have an impact on human health. This graph shows how health risks increase if the world fails to cut emissions or prepare for the impacts of climate change.
The larger the segment in each section, the greater the risk. The red segments show how much risk there is with current levels of adaptation, the yellow segments show how much this is reduced if policymakers take immediate action to address the threat.
Until 2050, the IPCC says climate change will mainly exacerbate existing health problems. The world’s poorest countries are likely to get hit the hardest.
The number of people expected to get injured or die from fires and heat waves is expected to rise as temperatures increase. Populations will also be increasingly at risk from waterborne diseases and those carried by bugs like mosquitoes.
The IPCC says there is likely to be a small reduction in the number of cold-related deaths. But this is far outweighed by the increase in the number of people experiencing health problems as a result of climate change.
7: Straining crop yields
Climate change is likely to change crop yields in the coming decades, putting a strain on food production, the IPCC projects. This graph shows when climate change might affect crop yields, if there is no effort to adapt to changing conditions.
The colour of the bars relates to whether yields will increase (the blue blocks) or decrease (yellow blocks). Each bar represents a 29-year period. The size of the block shows how many of the studies the IPCC reviewed predict the changes.
The IPCC estimates climate change will reduce average crop yields by between zero and two per cent each decade for the rest of the century. At the same time, demand is expected to increase by about 14 per cent per decade.
That could put a strain on food production in some areas, the IPCC says, particularly in poor regions. Because conditions won’t change in the same way everywhere, some areas may experience increased yields as the climate changes.
8: Cut emissions
This graph shows how emissions need to change between now and 2100 if the world is going to avoid the worst impacts of climate change:
Each of the coloured strips represents a different emissions pathway – or scenario – that the IPCC models.
There’s about a 66 per cent chance of keeping warming to two degrees if the emissions concentration stays between 430 and 480 parts per million (ppm) of carbon dioxide equivalent by 2100, the IPCC estimates – the light blue strip on the graph above.
If the emissions concentration rises to more than 580 ppm by 2100 it becomes “unlikely” the world will keep to the two degrees target, the IPCC says – the orange, purple, and grey strips.
The IPCC says that to give the world a decent chance of getting down into the light blue strip – and keeping the two degrees pledge – countries will have to make “substantial cuts” to their emissions by the middle of the century.
9: Act now
The longer the world leaves it, the greater those emissions cuts will have to be. The IPCC says that if emissions keep rising, countries will have to make considerably greater cuts towards the middle of the century to avoid the worst impacts of climate change.
This graph shows the level of cuts needed between 2030 and 2050, depending on how much the world emits before then:
It shows that if countries emit less than the equivalent of 50 gigatonnes of carbon dioxide between 2005 and 2030, they will need to reduce emissions by around three or four per cent a year (the dark green bar) between 2030 and 2050.
If countries emit more than 50 gigatonnes by 2030, they will have to make cuts of closer to five or six per cent a year between 2030 and 2050 (the lighter green bars).
If it gets to that stage, countries may find themselves relying on geoengineering solutions to extract carbon dioxide from the atmosphere, the IPCC says.
10: Transform the energy sector
Policymakers are going to have to find ways to incentivise huge amounts of investment in low carbon energy technologies if they are going to sufficiently cut emissions, the IPCC says.
This graph shows how much annual investment the IPCC expects to be needed across the next 20 years:
The IPCC estimates global investment in low carbon energy sources will need to increase by $147 billion a year if the world is going to cut emissions enough to prevent warming of more than two degrees. It says investment in conventional fossil fuel generation, such as coal and gas, will need to decrease by about $30 billion a year at the same time.
Energy efficiency will need the most additional investment, however. The IPCC says that companies will need to invest an extra $336 billion a year improving the efficiency of factories, buildings, and transport if the world is going to sufficiently reduce emissions.
For more information…
The IPCC’s report was an impressive undertaking. Reducing its findings to just 10 charts certainly doesn’t do it justice. Now you know the headlines, why not explore the details?
You can find the full reports on the IPCC’s website .