The climate is changing and human activity appears to be to blame, yet people still question the scientific evidence. Why do you think that is? Can there be any doubt?
There is no doubt. This is basic physics and chemistry that has been known for 150 years. The relationship between the level of carbon dioxide (CO2) in the atmosphere and the surface temperature of the planet was established by the physicist John Tyndall in 1864 and the physical chemist Svante Arrhenius in 1896.
I think that people argue about the science because it has huge implications for the way we live our lives. That’s what people are struggling to come to grips with, and perhaps it’s human nature to question the science rather than look for solutions.
Fossil fuels, land use change, and the manufacture of cement have contributed to the build up of CO2 in the atmosphere. Coal has been a huge factor because even though it produces nearly twice as much CO2 as natural gas it is still being burnt in increasing quantities because it is abundant and cheap.
Many scientists believe the effects will be hard to manage if society fails to keep global temperature rises below 2°C compared to the pre-industrial era. Can we succeed?
The problem is the total amount of carbon that accumulates in our atmosphere over time. To simply reduce the rate of emissions isn’t good enough because the total amount of carbon in the atmosphere will still rise. Man-made emissions must fall to nearly zero and that’s tremendously difficult to achieve.
Shell’s future energy scenarios don’t see the 2°C objective being met. However, they do suggest that you can bring emissions down to nearly zero within this century and effectively stop the further build-up of CO2 in the atmosphere.
What lies ahead if people don’t deal effectively with the problem?
The one thing we will collectively regret most is that sea levels will just keep on rising.
Many people don’t realise that the climate system is very sensitive and that small changes in global temperature have very big impacts on sea levels. For example, during the last ice age when global temperatures dropped by only 4-5°C, sea levels fell by 135 metres.
It’s unlikely to affect anyone in their own lifetime, but in the lifetime of cities like London, New York, Mumbai and Shanghai it is something to think about. Sea level rises could submerge some island nations, flood heavily populated coastal areas of many countries, and even force entire cities to move to higher ground.