A few days ago on 6 October 2018 the Intergovernmental Panel on Climate Change (IPCC) issued a special report on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Previously, the IPCC goal was to stop global warming at 2 °C above pre-industrial levels.
This very impressing and complex report contains a Summary for Policy Makers, Headline Statements and five large chapters with references and annexes.
As usual for IPCC and other intergovernmental organization; it’s more about politics and society than about science, and the report is probably mainly made for supporting the ongoing international climate negotiations, which recently have run into obstacles and difficulties!
In the following I will discuss some of the issues and weak points in the Summary for Policymakers and its references:
- In the report section A1, It is stated, that human activity is estimated to have caused approximately 1.0±0.2 °C of global warming above pre-industrial levels, and that the Global warming is likely to reach 1.5°C between 2030 and 2052, if it continues to increase at the current rate.
That development was illustrated in the following selection of a figure from the report:
That statement assumes that all increases of global warming and temperature in that time period are of anthropogenic origin, because the atmospheric anthropogenic greenhouse gas emissions and the concentration of CO2 in the atmosphere have increased similarly. The cumulative emissions have been about 2000 GtCO2 (or 600 GtC recalculated by me) and the annual anthropogenic emissions were presently estimated to about 40 GtCO2 and with an increase to > 52 GtCO2 in 2030. A temperature increase ranging between 0.22°C and 0.68°C per emission of 1000 GtCO2 (300 GtC) was estimated by IPCC.
Note: In the carbon cycle the unit Giga tons carbon (GtC ) is normally used but that will result in <3 fold smaller and less alarming figures than using GtCO2!
Such associations between two or more factors with similar trends are much used in epidemiology but it is well-known, that such associations often are not causal but false positive. A famous example is the association between numbers of children born and the numbers of storks living in the same area!
Regards the climate a confounding factor may be that the increasing temperature by definition will increase the atmospheric concentration of CO2, if the surface sea water layer is saturated (discussed later). In addition, for example, the increase of the world population has a similar trend.
It is a fact that about 1000 years ago, there was a natural period of warm climate in Greenland and warmer than nowadays. At that time the anthropogenic CO2 emissions were not of importance, and the atmosphere contained less CO2. The warmer climate made it easier than now to produce agricultural products, and the inland ice cover was less. That has been documented by that the recent melting and retreats of glaciers have revealed relics of houses from that time.
However, IPCC supposes in their models that there in the last 100-200 years has been no important natural warming and related temperature variations, and that the natural background temperature has been constant since preindustrial time (1850-1900)! That is of course bullshit!
The climate has ever been changing with or without human influences. There are and have always been natural, non-manmade temperature/climate variations and fluctuations but it is difficult to quantify and separate them from the present anthropogenic impact.
The importance of natural variations is illustrated by Al Gore’s prediction from 2007, when he (and IPCC) received the Nobel Peace Prize. He predicted that the Arctic icecap in 7 years’ time would disappear completely in the “summer”.
Nevertheless, in 2014 after these seven years the Arctic icecap was thicker and covered a much larger area than in 2007. Thus, he was not right in his statement – but such alarming statements easier get the attention of the press and public!
Every year the Arctic icecap is most thin and small during September month. A few weeks ago on 23 September 2018 the Arctic icecap had this year’s minimum extent (see picture from http://nsidc.org).
Picture of the present Arctic icecap extension
This extension in 2018 is a little less than in 2014. This is illustrated by the diagram below; I have drawn it, on basis of a table with satellite data for the last 12 years measured by the same instrument and from a reliable source: http://nsidc.org/arcticseaicenews/
If IPCC’s view was correct, and the anthropogenic CO2 emissions alone are decisive for the Arctic warming and icecap extension, a clear downward trend of the icecap in this whole period was to be expected – as Al Gore also did expect! The explanation for the lack of downward trend in that period could be that it was a natural cool period?
Therefore, when IPCC now again only discusses anthropogenic sources and ignores clear natural climate impacts and variations, they make simplifications, – probably not to disturb their political message.
- In section B4.1 it is stated: With 1.5°C of global warming, one sea ice-free Arctic summer is projected per century. This likelihood is increased to at least one per decade with 2°C global warming.
This statement is in contrary to the about 40 years of satellite measurements of the Arctic icecap, and it is estimates based on models and pure guessing, such as Al Gore previously did, and it ignors the natural variations and modulations illustrated in the diagram above. The IPCC report discusses some scientific literature from 2013 and later, but ignores the actual up-to-date measurements and variations shown above.
- In 3.3.8 it is stated: Summer sea ice in the Arctic has been retreating rapidly in recent decades. During the period 1997 to 2014 for example, the monthly mean sea-ice extent during September decreased on average by 130,000 km² per year (Serreze and Stroeve, 2015). This is about four times as fast as the September sea-ice loss during the period 1979 to 1996.
It seems a biased selection of years without informing about the great variations and the newest data. Below a graph from the paper of Serreze and Stroeve (2015), which both illustrates the trend and the variations, however, it is somewhat manipulated by including data measured by three different instruments for the periods 1979-1987 (no trend), 1987-2007 (large trend) and 2008-present (no trend), by shortening the Y-axis the trend seems steeper and more serious, and if the three recent years are included the overall trend would be smaller. The large decrease from 1987-2007 could be caused by an underlying natural warm period.
The trend of Arctic icecap extension 1978-2014.
- In Section B4.3 it is stated: The level of ocean acidification due to increasing CO2 concentrations associated with global warming of 1.5°C is projected to amplify the adverse effects of warming, and even further at 2°C, impacting the growth, development, calcification, survival, and thus abundance of a broad range of species, e.g., from algae to fish (high confidence).
This seems to be a misunderstanding of the marine chemistry of CO2. When the sea water become warmer, then less of CO2 gas can be dissolved/contained in the waters and CO2 gas will leave the water phase and transfer to the atmosphere, like when a carbonized soft drink become warm. By that process the sea water will be less acid. Thus less acidification – not more acidification as stated!
- In 188.8.131.52 it is stated: Ocean waters have increased in sea surface temperature (SST) by approximately 0.9°C and decreased in pH by 0.11 units since 1870-1899.
These temperature and pH trends and differences cannot be caused by CO2 changes. It can be explained by the fact that millions of industries since preindustrial time have emitted large volumes of various non-gaseous acids to the environment.
The following figure from an EEA publication shows, that this IPCC statement is quite a simplification. There are many variations and differences, and the temperature increase has been especially large for the Baltic Sea:
In fact, this warming of the Sea has released a very large amount of CO2 from sea surface water and transferred the gas to the atmosphere. Possibly, that accounts for a larger CO2 air emission than the annual contribution from burning fossil fuels in the same period.