Understanding the impact of climate change on direct weather events

In late 2019, one of Australia's major commercial insurance companies, IAG, in collaboration with the National Centre for Atmospheric Research in the United States, released  a report outlining the increased severe weather which will occur as a result of climate change. The report models impacts at 1.5C, 2C and +/- 2 degrees Celsius and makes for better understanding of the direct weather events caused by climate change rather than the larger global impacts of melting polar ice, acidification of oceans, higher temperatures and mega storms.

The report should probably have garnered greater interest at the time of release given it was commissioned by a large commercial insurer. The overall tenor of climate debate in Australia and political dynamic would not have been conducive to ensuring it received sufficient attention.

Of note, IAG's perspective is "... the level of knowledge has now reached the stage where it is possible to make confident assessment of the impacts of climate change at larger scales and longer time frames with objective assessment of the associated levels of confidence.."  This, of course, contradicts those political naysayers who believe the evidence of climate change is still contestable.

The report provides key six assessments which are summarised briefly below and given events of the past few months, many of these assessments have been shown to be accurate -

1. While the frequency of named tropical cyclones in the Australian region, the proportion of the most destructive tropical cyclones has increased at the expense of the more weaker systems. Tropical cyclone risks are therefore expected to increase rapidly in south-east Queensland,  north-east NSW regional followed by coastal districts in Western Australia.
2. Intense short duration rainfall is expected to increase almost everywhere in Australia , resulting in more frequent flooding in urban areas and in small river catchments.  
3. Areas of large hail (2.0-4.9cm in diameter) and giant hail (>5.0cm in diameter) should progressively move southwards with a large increase in the risk to the regions inland from the Hunter River, southwards through the central and southern highlands of New South Wales and central to eastern Victoria.
4. The multi-day impacts of east coast lows on the south-eastern seaboard of Australia are expected to increase due to wind-driven rainfall ingress, flash and riverine flooding. 
5. Bushfire risk, as measured by the trends in fire danger indices is likely to increase in all locations nationally leading to more frequent and extreme events and longer fire seasons.
6. Sea level rise is expected to accelerate around the Australian coastline but at differing rates. It is notable that past assessments of sea level rise are lower than those that recent observations show.

In light of actual recent new data, the IAG report may yet prove to still under-estimate the full weather impact which will be felt sooner rather than later.

The report can be accessed at this link -
IAG - NCAR Severe weather in a changing climate report

Climate change - global temperature rises since 1860

Temperatures since 1860 have increased in heat with considerable movement upward from 1940 onwards with this trend line projected to continue for the next two to three decades unless action is taken to reduce Greenhouse gas emissions.

Australia since 1970 - less water and increasing droughts

Time-based data evaluation and mapping by the Bureau of Meteorology starkly demonstrates the historical pattern of less rainfall over the Eastern half of the Australian continent which has occurred over the past 40 years. The Eastern half of the continent, comprising the states of  Victoria, New South Wales and Queensland, produces most of the agricultural outputs whereas the Western half of the continent is semi-arid, arid to desert and cannot support food production. The impact of less rainfall will be continue to be an acute problem and one which requires faster adaptation than is currently the case. 

Australia's temperature increase since 1910

Australian Bureau of Meteorology

As the bush fires have caused an indelible impact on Australia during 2019 and 2020, the actual temperature data for the continent demonstrates the  extent of the increase of temperature particularly over the past forty years. This situation matched with lower rainfall, provides the perfect vector for widespread fires on the landscape.

NSW Rural Fire Service - prediction map for 4 January 2020

The NSW Rural Fire Service (RFS) map portrays the manner in which bush fires can spread and the scale of movement given specific climatic conditions, in this case extreme temperature and wind condition.

Eastern Australia January 2020 - burning and fires - the influence of climate change

NSW Rural Fire Service fire ground map

Summer in Australia each year brings the bush fire season with hot weather, low rainfall and high humidity matched with regular electrical storms with more lightning than precipitation. Over meteorological history, the peak period in Australia has tended to be around late January to February for bush fires. Increasingly however this high risk timeframe has come earlier and now commences at the end of Autumn in the preceding year. Temperatures have been hotter at earlier points in time and rainfall has become less dispersed over the land and more concentrated within the period when it does fall. Droughts or floods are the obvious, extreme result.

This measure of impact is the actual influence of climate change in its earliest form at around 1.3C to 1.4C temperature increase. Climate change does not mean that the planet will suddenly be a tropical hothouse as those whom deny human-induced change constantly state, but rather the extremities with weather are now amplified many times over.  This provides an early window into how severe the changes will be if the current inadequate or lack of action continues.

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2020 - the year ahead

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As 2019 draws to a close and the new year beckons, it is timely to reflect on the year past and the challenges coming in the year ahead. Above all else there are two which come to mind immediately being first, the economy (defined both international and domestic) and second climate change - which continues apace. These two challenges are inter-related in any case and deserve a holistic set of solutions which a range of governments seem unable or unwilling to address.

Solutions for the environment need to encompass an array of issues including energy generation policy and distribution networks, materiels usage and life cycles (across all manufacturing sectors), further development of renewable energy and reduction in fossil fuel reliance and of urgent attention, climate change adaptation for food production and general living. Without all of these matters being addressed concurrently, life for human beings on this planet will become increasing difficult with a potential 4C temperature increase now a viable possibility.

As far as the world economy can be viewed, the two major influences are Brexit and the US/China trade war. Brexit may be less pronounced than first thought as the European Union has already advised that it intends to press ahead with a Free Trade Agreement with the United Kingdom as soon as Brexit is finalised. The US/China trade war has led to repeated renegotiation and has not, as yet, eventuated into a complete trade suspension and is mainly a tit-for-tat use of tariff measures. Around the world however low wages, low inflation, low productivity and low interest rates are closer to stagflation than recession.

On the international relations front, 2020 will begin with the ongoing matters from 2019  - Brexit, the US/China trade conflicts, some scale back in the Syrian war due to the likely success of the Assad Government in finally winning the civil war and the ongoing internal violence in Afghanistan and Iraq. China will continue to press its claim to the South China Sea and North Korea, although quiet at present may resume some further missile tests.

Happy new year !