Today and on Monday the IPCC are reporting their latest findings on climate change. The reports are written by scientists and in places the amount of information can be overwhelming. Here are the key findings as I see them:
What is the IPCC?
It's an International Panel on Climate Change. Set up by the United Nations (UN) it is a group of scientists from around the world who volunteer their time. This is their 5th major report. Their previous report was published in 2007.
Why should we believe what they say when there are so many different opinions on climate change?
Whilst we can't say that any scientific modelling is 100% accurate, this is a very credible report. It is peer-reviewed which means thousands of scientists have been able to analyse the data and contribute to the findings. Since 2007 the number of climate observations around the world and the sophistication of weather modelling software have both improved.
What are the findings?
In a nutshell; climate change is happening and human activity is a major contributing factor.
What is happening?
CO2 levels are the highest they've been for 800,000 years. They've increased 40% since 1750 (start of industrialisation).
It is 'likely' (66-100%) that the last three decades have been the warmest for 1,400 years.
Sea ice is melting and glaziers are shrinking. Sea levels are unusually high over the last 2,000 years.
How much are humans to blame?
It is 'very likely' (95-100%) that most of observed increase in surface temperatures since 1951 has been caused by human influence.
Greenhouse gasses are the biggest contributor. They've contributed to a 0.5C-1.3C temperature rise since 1951.
There is now a greater confidence (95-100%) that human activity is also responsible for ocean warming.
What will happen in the future?
By the end of the century it is 'likely' (66-100%) globally temperatures will rise between 1.5C and 4.5C. This is a slight improvement from projections published in 2007 (2C to 4.5C). The change is a result of improved modelling techniques by scientists. It is worth stressing that the lower threshold (1.5C rise globally) is only possible if action is taken by the world's population to cut emissions. A rise of 4.5C (which is possible if human behaviour doesn't change) would have a major imp
Sea levels will continue to rise. It is 'likely' (66-100%) that Greenland and Antarctic ice sheets will contribute to sea level rises of 3cm - 20cm by 2100.
There will be changes to precipitation patterns but it is difficult to predict what the changes will mean for specific areas.
So what will it mean for London?
It looks like the main trend will be for fewer cold winter days and more hotter days and nights during the summer. We may see greater extremes of temperature leading to health risks similar to those experienced during a heatwave. This doesn't mean we will no longer get cold winters it just means there is a general warmer trend.
It is difficult to draw any firm conclusions on whether we will suffer more flooding or drought.