Professor Ray Bates:

Regarding Deputy Brian Stanley’s question on extreme rainfall events, in addition to the effects of global warming resulting from increased greenhouse gases, a fact no scientist doubts, there is natural climate variability in the background that can cover long periods. The Atlantic multidecadal oscillation covers a period of 70 years.

As I showed earlier, average Irish temperatures between 1900 and 2012 were increasing at twice the global average rate for many decades. Since 2007 they have been decreasing rapidly. For several decades we had no snow or frost during winter. It began to look like cold winters had gone for good, but then we had several cold winters in a row. This is primarily due to natural variability. Irish temperatures could not be increasing at twice the global average rate as a result of greenhouse gases. That is physically and virtually impossible. The effect of greenhouse gases is to warm the centre of continents at the greatest rate and the centre of the oceans at the slowest rate. Ireland is influenced by Atlantic temperatures. If we were to examine the effects of greenhouse gases in isolation, Irish temperatures would be increasing more slowly than the global average rates. This would be because of the physics associated with the slow warming of the oceans and the fast warming of the continents. The fact that our temperatures were increasing at twice the global average rate for several decades is down to natural variability associated with the Atlantic multidecadal oscillation. The fact that they are now decreasing rapidly is again down to natural variability.

There are theories about how the decreasing sea ice in the Arctic can influence extreme values. In respect of the report from the British Met Office, there was a meeting on extremes very recently. A statement was produced by the Met Office and there were statements from various newspapers. If one looks at the Met Office, one can see that it is extremely cautious. If one looks at the reports in the newspapers, one can see that they were completely different. One of the reports from the newspapers stated that the UK's spell of awful summers is set to continue. These were quite dramatic statements. If one looks at the Met Office's own statement, it said "there is some research to say some parts of the natural system load the dice to influence certain states of the jet stream". It also stated that there is some initial evidence to suggest that changes in Arctic climate may be making an impact. These are extremely cautious statements but the newspapers abandoned caution and did not report them in the same terms.

I do not know if that answers the question about extreme rainfall events but what I am saying is that there is a lot of natural variability. If the temperatures can increase at twice the global average rate and then start decreasing, that is an indication that rainfall may be experiencing a lot of natural variability as well. For every single degree the temperatures goes up by, the content of water vapour in the air goes up by about 6% but the rainfall extremes we have seen have been 200% to 300% of normal rainfall in recent years. The floods of November 2009 were associated with 200% to 300% of normal rainfall in the catchment area of the Shannon. This is not to be explained in terms of temperature increases of 1° or thereabouts. It is just totally outside that range. In my opinion, these are much more likely to be due to natural variability within the system than to greenhouse gas changes because the extremes were just so big.

In respect of the question about pan-European action and its political feasibility, I completely agree that it is extremely difficult. Our interests are to try to protect our agriculture from our own perspective and a European security perspective. I would suggest that every European country is very conscious of its own interests. As I mentioned in the introduction to my paper, there are three factors motivating action to reduce greenhouse gas emissions. One of them is climate change; another is energy security, which is a big factor; and the third is the possibility of economic benefit from the development of renewable technologies. The technologically advanced countries stand to gain in a big way from the development of renewable energy technologies. It is, naturally, a motivating factor from the point of view of their national interest to try to promote a change to renewables as quickly as possible. This was a very good thing but the countries that are promoting that have a different profile of emissions from us. They do not have 30% of their emissions coming from their agricultural sector. They are looking at their national interest as well as the climate picture and I suggest that we also must look at our national interest as well as the climate picture. We must be conscious of our global responsibilities in climate change but we must also be conscious of our national interest.

Senator Keane asked about the IPCC and what to recommend. I would not recommend anything beyond what the report commissioned by the UN Secretary General came up with in the aftermath of the last IPCC report. As members will remember, there was a phenomenon known as "Climategate" where all the e-mails between the scientists involved with the IPCC were released and there were various errors such as saying that the Himalayan glacier would be gone by 2035. The UN Secretary General in conjunction with the head of the IPCC commissioned a group report from the InterAcademy Council. The InterAcademy Council consists not of intergovernmental people, but people from the academies of science of the different countries. The UN Secretary General commissioned this report and if members are interested in this question, I recommend that they read it. It the 2010 report of the InterAcademy Council and is very easy to find. I cannot remember the length of it. I could have brought it along. It is quite long, has least 50 pages and makes various recommendations about the IPCC. The main one is transparency in everything the IPCC does. I would recommend that anybody who is interested in anything to do with the IPCC reads the report of the InterAcademy Council published in 2010.

In respect of Senator Mac Conghail's question about whether targets should be relaxed as a result of the recent suggestions that climate sensitivity may be somewhat less than previously feared, it is not for a scientist to suggest targets. It is for politicians to decide what the targets should be given the scientific evidence. It is not really a matter for the IPCC or scientists. The role of the scientist is to provide the scientific evidence in an objective, unbiased and honest way. It is the political responsibility of the legislators to then decide what emissions reductions should be on the basis of the evidence given. It is not up to people like me to suggest what emissions reductions should be.