Climate change is a big topic in disaster management. I have earlier outlined that claims of a big impact on severe weather by climate change (at least presently) are largely overblown. As a broader risk management issue climate change is a big one.

If left unchecked, climate change could have some huge, civilisation altering, consequences over the next couple of hundred years. This is a big risk for humankind and possibly the largest over a timescale of 100-300 years.

Which is why it really gets my goat to hear claims that the warming has stopped.

There’s three things that can happen to the extra heat being trapped by the atmosphere. You can warm the atmosphere, warm the oceans or melt ice. These three systems all interact, transferring heat between them. For the denialists claims to be correct, atmospheric warming, melting ice and oceanic warming would all need to be stable. So what are they doing?

Surface temperatures:

Line plot of global mean land-ocean temperature index, 1880 to present, with the base period 1951-1980. The dotted black line is the annual mean and the solid red line is the five-year mean. The green bars show uncertainty estimates. (from GISTEMP)

Ocean Temperatures

from NOAA/NODC

Ice

Firstly sea ice – it’s like the ice cubes in your drink. Melting it doesn’t increase your drinks temperature or increase it’s level, but it does show that your drink is warming up.

Then there’s land ice – most of which is locked up in Antarctica and Greenland.

Monthly changes in Antarctic ice mass, in gigatones, as measured by NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites from 2003 to 2011. The data illustrate the continuing loss of ice from the continent. The plots here depict results from five different IMBIE team members using different methods. The data have been adjusted to reflect new models of post-glacial rebound.

Monthly smoothed (purple) and unsmoothed (blue) values of the total mass (in Gigatons, Gt), of the Greenland ice sheet from GRACE March 2002-September 2012. The barystatic (“bary” refers to weight) effect on local sea level change is the volume of freshwater added or removed divided by the ocean surface area. It does not include the effects of water thermal expansion, salinity or the associated changes to the gravity field. Figure is after Velicogna and Wahr (2006).

So though surface temperatures may be steady over the last 8-10 years or so it’s quite clear that ocean temperatures are still increasing and that ice (both sea and land ice) is still melting. So the claim that the globe (as a system) isn’t warming is a load of hot air.

You can find excellent information (and myth busting) at Real Climate and Skeptical Science.

I do want to note that these graphs are for different variables over different timescales (usually due to the experiment that the graph is showing or the length of historical records). There’s plenty of data out there that you can go and view yourself. This page at RealClimate is a good starting point. NASA also has a good site on various climate variables here.