While wildfires are not unusual in Australia, the second half of 2019 and the beginning of 2020 has featured the most active fire months on record. Apart from the direct impact fires are having on the population, vegetation or animals, the scientific community has also expressed concern for the potential impact on the global climate.
The large clouds of smoke from these wildfires have been invading the Australian atmosphere and have injected millions of tons of carbon dioxide that could amplify the greenhouse effect with a further increase in global temperatures.
Satellite image shows the fire affecting the eastern tip of the state of New South Wales, Australia. Source: Aqua MODIS, NASA
Following the significant wildfire outbreak during the past couple of months, scientists are addressing how climate change could worsen this extreme situation. In addition to the impact of increasing greenhouse gas concentrations, the smoke generated by the fires is darkening the skies in Australia and other countries across the vast Pacific Ocean.
Satellite images are showing a menacing mist that is travelling around the world and dramatically reducing air quality. Scientists from the Australian Bureau of Meteorology say that the dark solid particles that trail through the skies of the southern hemisphere could even be deposited on the ice of Antarctica, which would reduce its properties of solar reflectivity and increase the rate of thaw.
Observations show that until the first week of January 2020, the fires in New South Wales had injected about 420 million tons of carbon into the atmosphere. The data provided by Pep Canadell, lead scientist of the Australian National Research Agency and executive director of the Global Carbon Project, is worrisome. According to The Guardian, that amount of carbon is equivalent to all the carbon emitted by the United Kingdom in one year.
Once part of the atmosphere, carbon dioxide traps energy and helps increase temperatures while causing heatwaves and more drought in other areas of the planet. Carbon dioxide is not easily eliminated and according to calculations of the Global Carbon Project, if a ton of CO2 is injected into the Earth's atmosphere today, 330 kilograms will still remain 100 years later.
This image of the GEOS-FP system using MODIS (Terra / Aqua) shows the global aerosol distribution on January 9, 2020. Dust (orange), sea salt (blue), nitrates (pink) and carbon (red). From the south of Australia you can see the trail of smoke that runs through much of the South Pacific, even reaching the Atlantic. Source: NASA
Another important aspect of the impact the large smoke clouds can have on climate is the radiative changes the airborne particles can provoke. Ian McKendry, a professor at the University of British Columbia in Canada, has shown in recent studies that the smoke and haze causes cooling at the surface, yet dark aerosols in the column of air may actually absorb solar energy, which warms that part of the atmosphere. However, there is a long list of studies showing the opposite side of the coin, that is, the surface cooling effect these aerosols could have in the long term, just like when a powerful volcano eruption occurs.
Australia's devastating fires have generated spectacular pyro-clusters like the one seen in this image. These large clouds of vertical development, help inject particles and gases such as carbon dioxide at high altitudes. Source: NASA
Apart from the gases generated by the wildfires, there is great concern about the burning vegetation and the impact that can have on the energy balance. Most of what has been scorched are eucalyptus, pine, large extensions of bushes, shrubs and even some areas of subtropical jungle in the state of Queensland. How long it takes to regenerate all the vegetation, that great sink of carbon dioxide, will be crucial for this ecosystem to recover from the severe wildfires.
Australia Fires Friday January 24, 2020. Source: Landgate
There are several theories about the future of fires and how they could impact the Earth’s climate. At this rate, the wildfires could very well end up competing with emissions derived directly from human activity and become the main source of greenhouse gas emissions. This scenario could increase the frequency of fires, thus enhancing what scientists call a positive feedback cycle.
The general consensus is that it is still too early to know if the fires in Australia will end up being a net source of carbon or if the scorched areas will regenerate again and help capture carbon. The new climate we live in impacts fires, which can potentially affect the weather, but the truth is that we are still not clear on where and when that turning point will be reached, if reached at all.