The Paris climate agreement seeks to limit global warming to 1.5℃ this century. A new report by the World Meteorological Organisation warns this limit may be exceeded by 2024 – and the risk is growing.
This first overshoot beyond 1.5℃ would be temporary, likely aided by a major climate anomaly such as an El Niño weather pattern. However, it casts new doubt on whether Earth’s climate can be permanently stabilised at 1.5℃ warming.
The report also found while greenhouse gas emissions declined slightly in 2020 due to the COVID-19 pandemic, they remained very high – which meant atmospheric carbon dioxide concentrations have continued to rise.
Greenhouse gases rise as CO₂ emissions slow
Concentrations of the three main greenhouse gases – carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), have all increased over the past decade. Current concentrations in the atmosphere are, respectively, 147%, 259% and 123% of those present before the industrial era began in 1750.
Concentrations measured at Hawaii’s Mauna Loa Observatory and at Australia’s Cape Grim station in Tasmania show concentrations continued to increase in 2019 and 2020. In particular, CO₂ concentrations reached 414.38 and 410.04 parts per million in July this year, respectively, at each station.
Growth in CO₂ emissions from fossil fuel use slowed to around 1% per year in the past decade, down from 3% during the 2000s. An unprecedented decline is expected in 2020, due to the COVID-19 economic slowdown. Daily CO₂ fossil fuel emissions declined by 17% in early April at the peak of global confinement policies, compared with the previous year. But by early June they had recovered to a 5% decline.
We estimate a decline for 2020 of about 4-7% compared to 2019 levels, depending on how the pandemic plays out.
Although emissions will fall slightly, atmospheric CO₂ concentrations will still reach another record high this year. This is because we’re still adding large amounts of CO₂ to the atmosphere.
Warmest five years on record
The global average surface temperature from 2016 to 2020 will be among the warmest of any equivalent period on record, and about 0.24℃ warmer than the previous five years.
This five-year period is on the way to creating a new temperature record across much of the world, including Australia, southern Africa, much of Europe, the Middle East and northern Asia, areas of South America and parts of the United States.
Sea levels rose by 3.2 millimetres per year on average over the past 27 years. The growth is accelerating – sea level rose 4.8 millimetres annually over the past five years, compared to 4.1 millimetres annually for the five years before that.
The past five years have also seen many extreme events. These include record-breaking heatwaves in Europe, Cyclone Idai in Mozambique, major bushfires in Australia and elsewhere, prolonged drought in southern Africa and three North Atlantic hurricanes in 2017.
1 in 4 chance of exceeding 1.5°C warming
Our report predicts a continuing warming trend. There is a high probability that, everywhere on the planet, average temperatures in the next five years will be above the 1981-2010 average. Arctic warming is expected to be more than twice that the global average.
There’s a one-in-four chance the global annual average temperature will exceed 1.5℃ above pre-industrial levels for at least one year over the next five years. The chance is relatively small, but still significant and growing. If a major climate anomaly, such as a strong El Niño, occurs in that period, the 1.5℃ threshold is more likely to be crossed. El Niño events generally bring warmer global temperatures.
Under the Paris Agreement, crossing the 1.5℃ threshold is measured over a 30-year average, not just one year. But every year above 1.5℃ warming would take us closer to exceeding the limit.
Arctic Ocean sea-ice disappearing
Satellite records between 1979 and 2019 show sea ice in the Arctic summer declined at about 13% per decade, and this year reached its lowest July levels on record.
In Antarctica, summer sea ice reached its lowest and second-lowest extent in 2017 and 2018, respectively, and 2018 was also the second-lowest winter extent.
Most simulations show that by 2050, the Arctic Ocean will practically be free of sea ice for the first time. The fate of Antarctic sea ice is less certain.
Urgent action can change trends
Human activities emitted 42 billion tonnes of CO₂ in 2019 alone. Under the Paris Agreement, nations committed to reducing emissions by 2030.
But our report shows a shortfall of about 15 billion tonnes of CO₂ between these commitments, and pathways consistent with limiting warming to well below 2℃ (the less ambitious end of the Paris target). The gap increases to 32 billion tonnes for the more ambitious 1.5℃ goal.
Our report models a range of climate outcomes based on various socioeconomic and policy scenarios. It shows if emission reductions are large and sustained, we can still meet the Paris goals and avoid the most severe damage to the natural world, the economy and people. But worryingly, we also have time to make it far worse.
Pep Canadell, Chief research scientist, Climate Science Centre, CSIRO Oceans and Atmosphere; and Executive Director, Global Carbon Project, CSIRO and Rob Jackson, Chair, Department of Earth System Science, and Chair of the Global Carbon Project, Stanford University
Welcome to Australia, a place that is the focus of regular reports that nearly every creature is ready and waiting to pounce. If it rains, it brings warnings of venomous snakes. If the weather is dry, then giant spiders can set up house in your power box.
But as Australia prepares once again to welcome many new citizens this Australia Day, it seems appropriate to take a closer look at how deadly our creatures really are.
There is no doubt Australia harbours venomous animals and encounters that can be traumatic and need a rapid emergency response.
We must we careful not to understate the impact of any encounters with venomous animals on families and the sufferers themselves. Nor must we play down the highly specialised management, effective treatment and medical care required.
But is this reputation of a land of deadly and aggressive creatures well founded?
Detail in the data
My colleagues and I recently published a review of hospital admissions and deaths caused by venomous animals in the Internal Medical Journal.
We sourced data from 2001-2013 from national hospital admissions and national coronial information, which showed more than 42,000 hospitalisations from venomous sting or bites. Most – not all – are shown in the graph, below.
Over the 12 years that’s an average 3,500 people admitted to hospital every year for a venom-related injury. This can be loosely averaged 0.01% of the Australian population per year, or roughly one in 10,000 Australians.
Allergy or anaphylaxis from insect stings such as bees or wasps were responsible for about one-third (33%) of hospital admissions, followed by spider bites (30%) and snake bites (15%).
Over the 12 years, 64 people were killed by a venomous sting or bite, with more than half of these (34) caused by an allergic reaction to an insect bite that brought on anaphylactic shock.
Of these, 27 deaths were the result of a bee or wasp sting, with only one case of a beekeeper being killed. Anaphylaxis to tick and ant bites combined caused five deaths, the box jellyfish caused three deaths and two deaths were from an unidentified insect.
Given there are 140 species of land snakes in Australia, snake bite fatalities are very rare, at 27 for the study period. To put that in perspective, the World Health Organization estimates that at least 100,000 people die from snake bite globally each year.
While it’s natural to be frightened of snakes, the reality is the number of deaths from snake bites in Australia is very small. In the same time frame, for example, figures from the National Coronial Information System (NCIS) show nearly 5,000 people died from drowning and 1,000 from burns in Australia.
Nevertheless, snake bites do hold the crown as the most common cause of death, with nearly twice as many deaths per hospital admission than any other venomous injury, making snakebite one of the most important issues to address.
Deadly creatures elsewhere
Understandably, living in a country with creatures that can potentially kill us is a daunting prospect. As you can see from the figures, though, they don’t kill as many people as you might think and other countries have their own potentially deadly creatures.
A sturdy Australian would surely quake at the thought of being faced with an offensive grizzly, with no amount of Crocodile Dundee-esk buffalo hypnotism techniques going to get us through that encounter.
Sure Australia also has sharks and crocodiles, but it’s important to note that the majority of our critters do not come after you.
Minimising the minimal risk
Our report, while giving a broad overview of envenoming trends in Australia, does raise more questions than it answers. Questions such as: who is most at risk and how can we support them? Do we need more localised guidelines? And how do we maintain knowledge for such a rare injury?
This work seeks to initiate new conversations in regard to potential gaps in knowledge in both the public and health domains, and find solutions. We’re currently seeking funding to continue this research.
From an individual or national public health perspective, we can’t make informed decisions until we have a much clearer picture of what’s going on. The big question is how can we manage this coexistence with the creatures around us, without being detrimental to people and the creatures themselves.
It comes down to understanding, appreciating and respecting the amazing diversity nature has provided us. We need to learn about prevention methods and understand correct first aid.
This, together with the ongoing research and improvements in clinical care and the accessibility, affordability, effective management and treatment of bites and stings in Australia, actually make it one of the safest places in the world, and certainly not one of the deadliest.
Current greenhouse gas concentrations could warm the world 3-7℃ (and on average 5℃) over coming millennia. That’s the finding of a paper published in Nature today.
The research, by Carolyn Snyder, reconstructed temperatures over the past 2 million years. By investigating the link between carbon dioxide and temperature in the past, Snyder made new projections for the future.
The Paris climate agreement seeks to limit warming to a “safe” level of well below 2℃ and aim for 1.5℃ by 2100. The new research shows that even if we stop emissions now, we’ll likely surpass this threshold in the long term, with major consequences for the planet.
What is climate sensitivity?
How much the planet will warm depends on how temperature responds to greenhouse gas concentrations. This is known as “climate sensitivity”, which is defined as the warming that would eventually result (over centuries to thousands of years) from a doubling of CO₂ concentrations in the atmosphere.
The measure of climate sensitivity used by the Intergovernmental Panel on Climate Change (IPCC) estimates that a doubling of CO₂ will lead to 1.5-4.5℃ warming. A doubling of CO₂ levels from before the Industrial Revolution (280 parts per million) to 560ppm would likely surpass the stability threshold for the Antarctic ice sheet.
As the world warms, it triggers changes in other systems, which in turn cause the world to warm further. These are known as “amplifying feedbacks”. Some are fast, such as changes in water vapour, clouds, aerosols and sea ice.
Others are slower. Melting of the large ice sheets, changes in the distribution of forests, plants and ecosystems, and methane release from soils, tundra or ocean sediments may begin to come into play on time scales of centuries or less.
Other research has shown that during the mid-Pliocene epoch (about 4.5 million years ago) atmospheric CO₂ levels of about 365-415ppm were associated with temperatures about 3–4 °C warmer than before the Industrial Revolution. This suggests that the climate is more sensitive than we thought.
This is concerning because since the 18th century CO₂ levels have risen from around 280ppm to 402ppm in April this year. The levels are currently rising at around 3ppm each year, a rate unprecedented in 55 million years. This could lead to extreme warming over the coming millennia.
More sensitive than we thought
The new paper recalculates this sensitivity again – and unfortunately the results aren’t in our favour. The study suggests that stabilisation of today’s CO₂ levels would still result in 3-7℃ warming, whereas doubling of CO₂ will lead to 7-13℃ warming over millennia.
The research uses proxy measurements for temperature (such as oxygen isotopes and magnesium-calcium ratios from plankton) and for CO₂ levels, calculated for every 1,000 years back to 2 million years ago.
Some other major findings include:
The Earth cooled gradually to about 1.2 million years ago, followed by an increase in the size of ice sheets around 0.9 million years ago, and then followed by around 100,000-year-long glacial cycles.
Over the last 800,000 years, and particularly during glacial cycles, atmospheric greenhouse gas concentrations and global temperature were closely linked.
The study shows that for every 1℃ of global average warming, Antarctica warms by 1.6℃.
So what does all this mean for the future?
Global warming past and future, triggered initially by either changes in solar radiation or by greenhouse gas emissions, is driven mainly by amplifying feedbacks such as warming oceans, melting ice, drying vegetation in parts of the continents, fires and methane release.
According to the new paper, such greenhouse gas levels are committing the Earth to extreme rises of temperature over thousands of years, with consequences consistent with the large mass extinctions.
The IPCC suggests warming will increase steadily as greenhouse gases increase. But the past shows there will likely be abrupt shifts, local reversals and tipping points.
Abrupt freezing events, known as “stadials”, follow peak temperatures in the historical record. These are thought to be related to the Mid-Atlantic Ocean Current. We’re already seeing marked cooling of ocean regions south of Greenland, which may herald collapse of the North Atlantic Current.
As yet we don’t know the details of how different parts of the Earth will respond to increasing greenhouse gases through both long-term warming and short-term regional or local reversals (stadials).
Unless humanity develops methods for drawing down atmospheric CO₂ on a scale required to cool the Earth to below 1.5°C above pre-industrial temperature, at the current rate of CO₂ increase of 3ppm per year we are entering dangerous uncharted climate territory.
The link below is to an article that lists the ’10 most dangerous animals in Australia.’ However, you may find some of these animals not quite as dangerous as the author of this article would have you believe.
The link below is to an article that takes a brief look at our most dangerous animals.