It is extraordinary that 2021 was among the hottest years since the beginning of the Industrial Revolution. In the past, a La Nina year was a globally cool year, a time for a break from warmest weather. Now, a La Nina year is a globally very hot year. I am concerned of what the next super El Nino will bring, when temperatures do get seriously hot.

Temperature fluctuations associated with the Southern Oscillation (El Nino/La Nina) and other short-term cycles cannot conceal the remorseless upward trend in global temperatures. This La Nina year was hotter than El Nino years only a decade ago. Despite the need for urgent action, the Australian government remains committed to doing as little as possible to reduce emissions in Australia, and nothing that would limit our exports of coal and gas.

Just as in terrestrial systems, marine heatwaves (MHWs) are increasing in their frequency, intensity and duration, often resulting in substantial stress or mortality among marine organisms. In the absence of knowledge about the impacts of MHWs at the base of ocean foodwebs, we have limited understanding of the ecological risks from MHWs to fisheries and the rapidly growing aquaculture sector. This translates to significant uncertainties in ecosystem predictions and projections that are critical for risk management and developing appropriate adaptive strategies and policies.

The study uses the best available worldwide information to evaluate global temperature records and ranks 2021 in the top 7 hottest years on record. I look to the WMO to provide the most accurate outlook on the climate, and as a marine scientist working on biological responses to warming, this analysis is both trustworthy and concerning.

Our temperature record is now long enough for scientists to be able to attribute anthropogenic warming as opposed to natural variability.  We know that warming is not occurring evenly around the globe and that some people may even welcome warm seawater temperatures where they go swimming and surfing.

However, the increasing record-breaking temperatures are already inflicting harm on marine ecosystems, with well documented impacts of coral bleaching, and massive biodiversity loss during marine heatwaves.

How organisms will respond to more frequent, extreme and unpredictable changes in their environment remains little known, and is slated by the IPCC as urgently required if we are to manage its consequences for human society.

We know that the Earth has warmed on average by 1.2 degrees since the pre-industrial period, and climate science is unequivocal that it is human-emitted greenhouse gases that have caused this warming.

It is important, however, to distinguish between climate change and climate variability. Climate change refers to the effects of long-term global warming, such as an increasing frequency and intensity of extreme weather events. Climate variability refers to the natural oscillations of regional climate conditions around this long-term trend. 

One of the best known of these is El Niño – and its sister, La Niña. We are currently in a La Niña phase which typically brings wetter and more stormy weather to eastern Australia. The occurrence of La Niña, and cooler seasonal temperatures, in no way contradicts the clear existence of a warming trend. In fact, the WMO report published today shows that despite back-to-back La Niña events in 2020-2022, 2021 was still one of the warmest years on record. There is also an increasing body of research that suggests that global warming may even increase the strength of El Niño and La Niña events, by injecting more energy into the Pacific circulation system.

The report helps explain why the eastern states are less hot and subject to bushfires this summer (due to La Niña) but in the west we are not impacted by that.

Hence we have seen three towns over 51 degrees last week in our north, and the second heat wave now happening in Perth with 41 today and over 40 expected all week. 

We are getting the full blast and bushfire alerts are everywhere.

The recent report from the World Meteorological Organization suggests that any perceived lull in global climate change is not a source of hope that warming is decelerating. Rather, average temperatures continue to be far above what you would expect at this time in the ENSO cycle.

What do reports like this mean for Australia? They might mean that we need to think about how the places that we love and work in will be affected, and how we will need to adapt to deal with heat and changing rainfall patterns, bushfires and coastal erosion. Many of our near neighbours are going to be the most vulnerable to climate change on Earth, so it might also mean that we need to think more about how we interact with other countries, especially as there is a new level of intolerance of countries that are not pulling their weight to reduce GHG emissions.

We are experiencing a La Nina event this summer, but as the WMO notes, this short period provides only temporary relief in amongst a long-term trend of global warming. This report, and others like it, need to be used to trigger political and technological change. Australia is making small steps, but if we are not going to experience more and more extreme weather events, we need to think about how we could adjust our society so that we can help lead a global response to the climate crisis.

While La Niña has provided temporary cooling, the human fingerprint of climate change is evident in 2021 being on the seven warmest years on record. We are getting close to the limit of 1.5°C global warming that we have collectively set for ourselves through the Paris Agreement in order to avoid the most dangerous climate change impacts.

If we rapidly reduce our greenhouse gas emissions we may be able to stick to the Paris Agreement, but at the moment, we're heading for global warming exceeding 2°C and that will come with much worse heatwaves, more extreme rainfall, and the end of our coral reefs. On our current trajectory we'll have very few years as cool as 2021 again, but if we make major efforts to decarbonise our economy and society then we can avoid leaving behind a much more dangerous and inhospitable climate for future generations to manage.

The combined impacts of climate change will increase the frequency and magnitude of coastal hazards such as erosion and flooding.

Particularly, densely populated areas along sub-tropical Queensland and New South Wales will be increasingly exposed to these hazards due to a progressive increase in sea-level, stronger cyclones reaching further south and the anti-clockwise rotation of waves in the coming decades.

We need to reduce CO2 emissions and better adapt to these hazards if we want to avoid predictable and costly disasters for coastal communities.

There are two confronting things here, one is the near record warmth despite the strong cooling influence of a La Niña. The other is that on the current trajectory we are well on our way to 1.5°C warming in about a decade from now.  And 2°C will follow around mid century, unless drastic measures are taken to curb fossil fuel extraction and burning.