Global temperatures are now 1.0 degree above the adpted 1870 baseline (UK Met Office, 2016).
Climate Change
"Anthropogenic climate change is unfortunately a very significant risk to the long term continuation of human society on earth, as we know it."
Anthropology of Climate Change
The risk that carbon based climate change poses to modern society should not be overlooked.
Small changes in climate have played a role in the collapse of past societies. The collapse of the Nordic community on Greenland during the late 15th century has been attributed to a short term decrease in local temperatures of around 0.5 degrees Celsius (Diamond, 2005).
Over the next century, global temperatures may well reach over 4 degrees above pre-industrial. Global temperatures have not reached these levels since the middle of the Miocene epoch, around 14 million years ago.
Modern Climate Change History
A carbon based mechanism for climatic warming was proposed by Svante Arrhenius in 1896. Experimental evidence confirming a pattern of continually increasing atmospheric carbon dioxide levels was published in 1960, by C. Keeling.
By the late twentieth century the vast majority of the impartial scientific community had accepted the general principles of anthropogenic climate change. Today the broader community is very much aware of the link between atmospheric carbon and increasing global temperatures, and the potential for significant long term global average temperature increases.
Recent attempts at global co-operation to reduce the causes of anthropogenic climate change, such as commitments made at the Paris COP 21 UN Climate Summit, have produced strong rhetoric around capping global temperature increases to 2.0 degrees C above pre-industrial, with an aspirational goal of 1.5 degrees C. General scientific consensus is that the ecological and societal impacts of a global average temperature increase of between 1.5 and 2.0 degrees C will be create many challenges, but should still be managable.
Unfortunately emissions to date and continuing fossil fuel usage trends mean that we are on track for global average tempertures well above levels generally considered to be "manageable" in terms of impacts on natural and agricultural ecosystems.
Greenhouse gases trap infrared radiation
causing an increase in surface temperature.
Copyright S. Brink.
UK Met Office Global Average Temperate Climatic Data, 2017
Global fossil fuel use continues to increase.
Where is Our Climate Heading?
In 2016, global average temperatures reached 1.0 degree above the adopted 1870 baseline year for the first time, (UK Met Office, 2016). As the industrial revolution actually began in 1750, warming that occurred between 1750 and 1870 (0.2 degrees C) also needs to be accounted for, so average temperatures in 2016 were actually 1.2 degrees Celsius above a "genuine" pre-industrial baseline (Dunlop, 2016).
Some further temperature increases may already be "locked in", due to temperature increases lagging behind greenhouse gas emissions due to temperatue stabilisation from melting ice, ocean temperature stratification and a geological heat sink effect. Temperature lag may be significant, and could be as much as 0.6 degreees celcius (The Conversation, 2014).
A further temperature increase can also be expected when reflective sulphate pollutants from coal fire power stations that have a global cooling effect, are removed from our atmosphere, as these power stations are eventually phased out. This increase has been estimated to be as much as 0.5 degrees celcius, (Mann, 2015).
"Greenhouse gas emissions to date are expected to cause warming of more than 2.0 degrees Celsius above pre-industrial, even if greenhouse gas emissions were to end overnight. " (S. Brink, 2017)
So where to from here?
If greenhouse gas emissions continue in accordance Paris COP 21 commitments, (i.e. full fossil fuel use being phased out by 2100), temperatures can be expected to be around 4 degrees Celcius above pre-industrial by early next century.
"The consequences of a 4 degree celsius temperature increase above pre-industrial are immense. Widespread agro-economic, ecological and even human population collapses, are possible, and perhaps even likely? "
Significant Ecosystem Changes are Expected with a 4 Degree Celsius Increase in Global Temperatures
Solar Dynamic Climatic Fluctuations
The identification of solar magnetic cycles (Zharkova, et al, 2015) is now providing an improved understanding of non-anthropogenic climatic variations. Solar dynamo models are suggesting that we may have some relief from anthropogic climate change during a period of reduced solar activity predicted to occur between 2020 and 2053. Historic climatic data suggests that temperature decreases averaging around 0.5 degrees Celcius typically occur during these 'Maunder Minimum' cyclic periods of reduced solar activity.
The temperature decrease is expected to be greatest at the solar activity minimum, projected to occur between 2028 to 2032.
Beyond 2050, solar activity is expected to return to levels similar to current levels. Modeling by Zharkova suggsts that these periods of reduced solar activity occur every 350-400 years.
Copyright S. Brink.
Climate Projections
Based on the above, future climate projects can be model and are presented below.
Global average temperature decreases are expected between 2020 and 2053 due to the next Maunder Minimum
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Copyright S. Brink.
Temperature Projections Under Various Greenhouse Gas (GHG) Emission Scenarios
Copyright S. Brink.
What can we do about climate change?
The climate change challenge can seem huge. How can we as an individual, a community and even as a country, make any significant contribution to such a huge global challenge? Society, as we know it, has been developed by utilising cheap abundant fossil fuels. We do have some energy alternatives, but the economic, strategic and geopolitical complexities of transitioning to "low carbon" energy sources have been largely unresolvable to date.
One area of climate change mitigation that is often overlooked in popular debate is the potential role of "enabling technologies". A new technology could potentially have a very significant positive impact on our global climate future, by enabling a global "energy shift" to low carbon energy sources.
An "energy shift" to a low carbon future will still ultimately need a co-ordinated global strategy, but the availability of new cost effective low carbon technology could make it far more attactive for governments to pro-actively implement a rapid shift to non-carbon energy alternatives.
Are We Due for
Another Ice Age?
Ice core data shows temperature variations in the past 10 million years have varied between the pre-inductrial average temperature and approximately
8 degrees below this.
At some stage we are most like to return to cooler temperatures, but large temperature transitions have, in the past, been relatively slow, occuring over thousands of years, so such a transition is highly unlikely to make any significant contribution to resolving the current climate change crisis.
Copyright S. Brink.
"Perhaps our best realistic change of mitigating climate change is the development of new, very low cost, zero carbon energy technologies in the near future, that will give global policy makers the confidence to implement a full global phase out of greenhouse gas emissions before 2050, limiting global warming to around 3 degrees above pre-industrial."
References:
Diamond, J., 2011, Collapse: How Societies Choose to Fail or Succeed,
Revised Edition, ISBN-10: 0143117009, ISBN-13: 978-0143117001, first published in 2005.
Dunlop, I., 2016, Engineers Australia Presentation - Our Climate Emergency
Live presentation and webinar
Live presentation and webinar
UK MET Office, 2016, Global climate in context as the world approaches 1°C above pre-industrial for the first time, www.metoffice.gov.uk, accessed 20/12/16
Mann, M, 2015, How Close Are We to ‘Dangerous’ Planetary Warming?
The Huffington Post, 12/23/2015 03:37 pm ET | Updated Dec 23, 2015
The World Bank, 2012, Turn Down the Heat - New Report Examines Risks of 4 Degree Hotter World by End of Century
Accessed via www.worldbank.org
New York City Panel on Climate Change, 2015, REPORT: Sea Level Could Rise by 6 Feet in New York by 2100.
publichealthwatch, accessed 21st Dec 2016, publichealthwatch.wordpress.com
The Conversation, 2014, What would happen to the climate if we stopped emitting greenhouse gases today?
Published at: theconversation.com