Comments gcolbourn has made

2% a year will not get 80% by 2050

Hi,

danielbell says that we need 2% cuts in emissions per year to get to 80% cuts by 2050. This is a common misconception. It is 2% of todays emissions that he means. However, year on year, a 3.76% cut in emissions is needed (based on the 'compound interest' formula 100.0*(1 - E^((Log[(100 - 80)100])(2050 - 2008))). you can check by doing (100-3.76)^42.

However, there is mounting evidence that 80% by 2050 is woefully inadequate. If anyone has read the book Heat by George Monbiot (a well known writer on environment and social justice issues in the UK), they will be familiar with 90% by 2030, which is what he reckon's will be needed to avoid 'runaway' climate change. This is a 10% year on year cut. [He now actually reckons that even this will be inadequate, but best not to dwell on that!]

2050 is a too distant target. We need the biggest cuts soonest. Having a target so far in the future is dangerous in terms of people thinking we have plenty of time to deal with the issue. We need the biggest cuts soonest, because it is the total amount emitted that is important, not the eventual reduction in rate of emissions. I suggest 5% year on year maybe achievable politically, even though it may prove to fall short scientifically!

Ultimately, we need to reduce emissions to a level that is below the level that natural 'sinks' can deal with, so that the level of GHGs in the atmosphere actually diminishes (rather than just merely rising more slowly). We may already be beyond the safe limit - some are now touting 400ppm CO2e (we are currently at c. 430ppm CO2e). The problem is also that the sinks may be becoming saturated, so are themselves diminishing. 80% by 2050 is admirable, but unless the bulk of that 80% happens before 2020 or 2030 it won't be enough.

"I find it helpful to think of the three deadly C's. Cars, cattle and chain saws." - James Lovelock