“Unless we take action on climate change, future generations will be roasted, toasted, fried and grilled” Ms Christine Legarde, Managing Director IMF
Science proceeds cautiously. A hypothesis is in favour and dominates thinking for a period of time until evidence from the natural world suggests that the hypothesis needs correction or a fundamentally different hypothesis replaces the original one. When we modify and adjust a hypothesis we refer to this as a “refinement”; when we replace it is called a paradigm shift.
Part of the problem with climate science is that many of its proponents gave up on actual evidence some time ago and instead prefer to spend their time looking at the output from a range of computer models which, though they utilize some actual evidence, do so within a range of pre-programmed assumptions. The IPCC, for example, develops scenarios based on these models and most predictions we see from climate scientists also have their origins in these models.
Science is also about exceptions – an event or series of events which challenge the dominant hypothesis. For example, unusual occurrences in a chemistry experiment sometime send chemists in new directions, just as lab mistakes have created new substances (e.g. aspartame). So when a pattern changes, we take note.
The dominant hypothesis of the current favoured climate science has these components:
1. Human activity science 1945 is causing a significant increase in CO2 emissions.
2. CO2 emissions accumulate in the atmosphere together with other greenhouse gasses and add to naturally occurring CO2.
3. CO2 and other greenhouse gasses in the atmosphere have an impact on climate, acting as a “greenhouse” especially when coupled with assumed climate forcing elements.
4. The net impact of the greenhouse effect and climate forcing is warming.
5. Warming as measured by the global mean surface temperature will cause erosion of the ice at both poles of the earth, which in turn will have an impact on ocean sea levels.
6. Warming will also have an impact on weather events, biodiversity and human activity.
So the core hypothesis is this: “Increasing anthropogenic emissions of carbon dioxide have a significant warming effect on global climate”.
Carbon dioxide in the atmosphere is 39/1,000ths of one percent. Ninety-five percent of the greenhouse effect is water vapor, and the level of water vapor in the atmosphere is not changing. The total change in atmospheric composition since 1945, when CO2 levels began to increase, is one 9/1,000ths of one percent. The climate models all assume that this is significant and will have a significant impact. They are wrong.
Indeed, the models used to predict climate are “out” by 10C – more than the climate has changed since the dire warnings from some climate scientists began. We have now had 15 years without any significant warming, even though CO2 emissions have risen significantly. Fears of a 10C increase in global surface temperature per decade – the worst case scenario – appear to be unfounded.
Part of the argument favouring the dominant hypothesis is that a large number of scientists are aligned with it. There are claims, for example, that 97% of climate scientists agree with the hypothesis. This is not at all the case. a Canada-based group calling itself Friends of Science has just completed a review of the four main studies used to document the alleged consensus and found that only 1 - 3% of respondents "explicitly stated agreement with the IPCC declarations on global warming," and that there was "no agreement with a catastrophic view." The hypothesis as stated above remains dominant, but there are growing scientific concerns that the hypothesis is flawed. Some 32,000 American scientists have made clear that they disagree with the hypothesis.
Currently we can summarize evidence related to the hypothesis as follows:
Currently we can summarize evidence related to the hypothesis as follows:
· Warming: Analyses of data from a number of sources indicate that (i) there was a gradual increase in global atmospheric CO2 concentration from about 1860 to 1945, (ii) there has been a much more rapid rate of increase in atmospheric CO2 concentration from 1945 to the present, (iii) the most recent trend of global surface air temperature during this period of rapid CO2increase has been downwards, which is in contradiction to the predictions of the most sophisticated general circulational models of the atmosphere in use today, (iv) this downward trend in surface air temperature has been most pronounced in northern latitudes, which is also in contrast to the model predictions, and (v) the downward temperature trend has been greater in summer than in winter, which is again in contradiction to the models.
· Extreme Weather: Despite frequent political claims to the contrary, there is no established relationship between climate and extreme weather events. Indeed, the IPCC came to the conclusion that “there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century” and “current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century … no robust trends in annual numbers of tropical storms, hurricanes and major hurricanes counts have been identified over the past 100 years in the North Atlantic basin” and “there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale”
· Sea Level Rise: Records and research show that sea level has been steadily rising at a rate of 1 to 2.5 millimeters (0.04 to 0.1 inches) per year since 1900. This rate may be increasing. Since 1992, new methods of satellite altimetry (the measurement of elevation or altitude) indicate a rate of rise of 3 millimeters (0.12 inches) per year. Although fast, the observed rise still is (just) within the ‘natural range’.
· Arctic and Antarctic Ice: It is clear from the various data sets, terrestrial and satellite, that both the Arctic sea ice extent and multi-year ice volume are reducing. Sea ice extent recovered slightly during the Arctic winters of 2008-09, but the full extent of annual ice reduction or gain is seen in September of each year, at the end of the Arctic summer. The volume of multi-year ice has not recovered at all, and is showing a steeply negative trend. In the Antarctic things are different. Scientists at the British Antarctic Survey say that the melting of the Pine Island Glacier ice shelf in Antarctica has suddenly slowed right down in the last few years, confirming earlier research which suggested that the shelf's melt does not result from human-driven global warming.
So where does this leave us? It leaves us as scientists with a view that the core dominant hypothesis is failing to explain the complexity of the evidence we are seeing from actual measurements of what is happening in the atmosphere, oceans, on the ice and on the ground. While some have suggested that all is consistent with the dominant hypothesis, there is a growing sense that the hypothesis is weak and needs refinement or replacement.
Some have suggested that there is a range of natural variability which is not accounted for in current models and analysis (see here and here). Others have suggested that the influence of the sun is poorly accounted for in the current understanding of climate (see here).