El Niño

February on course to break unprecedented number of heat records

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https://www.theguardian.com/environment/2024/feb/17/february-on-course-to-break-unprecedented-number-of-heat-records

Experts struggle to explain how rises in sea-surface temperatures have accelerated so quickly. Photograph: PPAMPicture/Getty Images

Rapid ocean warming and unusually hot winter days recorded as human-made global heating combines with El Niño

February is on course to break a record number of heat records, meteorologists say, as human-made global heating and the natural El Niño climate pattern drive up temperatures on land and oceans around the world.

A little over halfway into the shortest month of the year, the heating spike has become so pronounced that climate charts are entering new territory, particularly for sea-surface temperatures that have persisted and accelerated to the point where expert observers are struggling to explain how the change is happening.

“The planet is warming at an accelerating rate. We are seeing rapid temperature increases in the ocean, the climate’s largest reservoir of heat,” said Dr Joel Hirschi, the associate head of marine systems modelling at the UK National Oceanography Centre. “The amplitude by which previous sea surface temperatures records were beaten in 2023 and now 2024 exceed expectations, though understanding why this is, is the subject of ongoing research.”

Humanity is on a trajectory to experience the hottest February in recorded history, after a record January, December, November, October, September, August, July, June and May, according to the Berkeley Earth scientist Zeke Hausfather.

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Continue ReadingFebruary on course to break unprecedented number of heat records

6 reasons why global temperatures are spiking right now

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Jonas Weckschmied/Unsplash

Andrew King, The University of Melbourne

The world is very warm right now. We’re not only seeing record temperatures, but the records are being broken by record-wide margins.

Take the preliminary September global-average temperature anomaly of 1.7°C above pre-industrial levels, for example. It’s an incredible 0.5°C above the previous record.

So why is the world so incredibly hot right now? And what does it mean for keeping our Paris Agreement targets?

Here are six contributing factors – with climate change the main reason temperatures are so high.

1. El Niño

One reason for the exceptional heat is we are in a significant El Niño that is still strengthening. During El Niño we see warming of the surface ocean over much of the tropical Pacific. This warming, and the effects of El Niño in other parts of the world, raises global average temperatures by about 0.1 to 0.2°C.

Taking into account the fact we’ve just come out of a triple La Niña, which cools global average temperatures slightly, and the fact this is the first major El Niño in eight years, it’s not too surprising we’re seeing unusually high temperatures at the moment.

Still, El Niño alone isn’t enough to explain the crazily high temperatures the world is experiencing.

2. Falling pollution

Air pollution from human activities cools the planet and has offset some of the warming caused by humanity’s greenhouse gas emissions. There have been efforts to reduce this pollution – since 2020 there has been an international agreement to reduce sulphur dioxide emissions from the global shipping industry.

It has been speculated this cleaner air has contributed to the recent heat, particularly over the record-warm north Atlantic and Pacific regions with high shipping traffic.

It’s likely this is contributing to the extreme high global temperatures – but only on the order of hundredths of a degree. Recent analysis suggests the effect of the 2020 shipping agreement is about an extra 0.05°C warming by 2050.

A smog shrouded road with motorcycles, trucks and cars barely visible through the pollution
People pass through the rising pollution on the Delhi-Jaipur Expressway in Gurgaon, Haryana, India, on November 12 2021.
Shutterstock

3. Increasing solar activity

While falling pollution levels mean more of the Sun’s energy reaches Earth’s surface, the amount of the energy the Sun emits is itself variable. There are different solar cycles, but an 11-year cycle is the most relevant one to today’s climate.

The Sun is becoming more active from a minimum in late 2019. This is also contributing a small amount to the spike in global temperatures. Overall, increasing solar activity is contributing only hundredths of a degree at most to the recent global heat.

4. Water vapour from Hunga Tonga eruption

On January 15 2022 the underwater Hunga Tonga–Hunga Haʻapai volcano erupted in the South Pacific Ocean, sending large amounts of water vapour high up into the upper atmosphere. Water vapour is a greenhouse gas, so increasing its concentration in the atmosphere in this way does intensify the greenhouse effect.

Even though the eruption happened almost two years ago, it’s still having a small warming effect on the planet. However, as with the reduced pollution and increasing solar activity, we’re talking about hundredths of a degree.

5. Bad luck

We see variability in global temperatures from one year to the next even without factors like El Niño or major changes in pollution. Part of the reason this September was so extreme was likely due to weather systems being in the right place to heat the land surface.

When we have persistent high-pressure systems over land regions, as seen recently over places like western Europe and Australia, we see local temperatures rise and the conditions for unseasonable heat.

As water requires more energy to warm and the ocean moves around, we don’t see the same quick response in temperatures over the seas when we have high-pressure systems.

The positioning of weather systems warming up many land areas coupled with persistent ocean heat is likely a contributor to the global-average heat too.

6. Climate change

By far the biggest contributor to the overall +1.7°C global temperature anomaly is human-caused climate change. Overall, humanity’s effect on the climate has been a global warming of about 1.2°C.

The record-high rate of greenhouse gas emissions means we should expect global warming to accelerate too.

While humanity’s greenhouse gas emissions explain the trend seen in September temperatures over many decades, they don’t really explain the big difference from last September (when the greenhouse effect was almost as strong as it is today) and September 2023.

Much of the difference between this year and last comes back to the switch from La Niña to El Niño, and the right weather systems in the right place at the right time.

The upshot: we need to accelerate climate action

September 2023 shows that with a combination of climate change and other factors aligning we can see alarmingly high temperatures.

These anomalies may appear to be above the 1.5°C global warming level referred to in the Paris Agreement, but that’s about keeping long-term global warming to low levels and not individual months of heat.

But we are seeing the effects of climate change unfolding more and more clearly.

The most vulnerable are suffering the biggest impacts as wealthier nations continue to emit the largest proportion of greenhouse gases. Humanity must accelerate the path to net zero to prevent more record-shattering global temperatures and damaging extreme events.The Conversation

Andrew King, Senior Lecturer in Climate Science, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue Reading6 reasons why global temperatures are spiking right now

We just blew past 1.5 degrees. Game over on climate? Not yet

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Ailie Gallant, Monash University and Kimberley Reid, Monash University

July 2023 was the hottest month ever recorded. And now we know something even more alarming. This week, the European Space Agency announced the July heat pushed the global average temperatures 1.5℃ above the pre-industrial average.

The ominous headlines seemed to suggest we’d blown past the 2015 Paris Agreement goal of holding warming to 1.5℃ – and around a decade earlier than expected.

Is that it? Game over, we lost?

Well, like all things to do with climate change, it’s not quite that simple. The threshold was breached for a month before average temperatures dropped back. And July 2023 isn’t actually the first time this has happened either – the dubious honour goes to February 2016, where we broke the threshold for a few days.

Remind me – why is 1.5℃ so important?

In 2015, the world looked like it was finally getting somewhere with action to combat climate change. After decades of arduous debate, 195 nations adopted the Paris Agreement, a formal but non-binding agreement with a clear goal: limit global warming to 1.5℃ above pre-industrial levels to avoid the worst effects of climate change.

But there’s nothing magic about this number. Every increase worsens the impacts. So why is 1.5℃ so important?

Essentially, it was thrashed out by experts as a threshold representing heightened danger. The Paris Agreement states avoiding dangerous climate change means keeping global temperatures “well below 2℃” of warming, and so the 1.5℃ threshold was born.

What’s a dangerous level of climate change? Basically, levels of warming where the damage becomes so widespread or severe as to threaten economies, ecosystems, agriculture, and risk irreversible tipping points such as the collapse of ice sheets or ocean circulations. More importantly, this level of warming risks pushing us beyond the limits of being able to adapt.

Put simply, the 1.5℃ threshold is the best estimate of the point where we are likely to find ourselves well up the proverbial creek, without a paddle.

Is it too late to act on climate change?

So, should we all just give up?

Not yet.

The global authority on climate change, the Intergovernmental Panel on Climate Change, defines 1.5℃ as a departure from global average temperatures above the 1850 to 1900 (pre-industrial) average.

It’s true that this threshold was exceeded for the month of July 2023. But the climate is more than a single month.

Global average temperatures go up and down every year on top of the global warming trend, because climates naturally vary year-to-year.

The most recent few years have been much warmer than average, but cooler than they could have been because of consecutive La Niña events.

This year, there’s been a significant acceleration in warming, largely due to the brewing El Niño event in the Pacific. El Niño years tend to be hotter.

To iron out year-to-year differences, we typically average data over several decades. As a result, a 2021 IPCC report defines the 1.5℃ threshold as the first 20-year period when we reach 1.5℃ of global warming (based on surface air temperatures).

Recent research shows the best estimate to pass this threshold is in the early 2030s. That means, by IPCC definitions, the average global temperature between the early 2020s and early 2040s is estimated to be 1.5C.

Dangerously close to the red line

All of this means we haven’t yet failed to meet our Paris targets. But the July record shows us we are dangerously close to the line.

As the world keeps heating up, we’ll see more and more months like this July, and move closer and closer to the threshold of 1.5℃, beyond which global warming will become more and more dangerous.

Is it still possible to stay below 1.5℃? Maybe. We would need extremely aggressive cuts to emissions to have a chance. Failing that, we will likely exceed the Paris target within the next decade or so.

Let’s say that happens. Would that mean we just give up on climate action?

Hardly. 1.5℃ is bad. 1.6℃ would be worse. 2℃ would be worse still. 3℃ would be unthinkable. Every extra increment matters.

The closer we stay to the line – even if we cross it – the better.

And there’s now good evidence that even if we overshoot 1.5℃, we could still reverse it by ending emissions and soaking up excess greenhouse gas emissions. It’s like turning around an enormous container ship – it takes time to overcome the inertia. But the sooner we turn around, the better.The Conversation

Ailie Gallant, Senior Lecturer, School of Earth, Atmosphere and Environment, Monash University and Kimberley Reid, Postdoctoral Research Fellow in Atmospheric Sciences, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingWe just blew past 1.5 degrees. Game over on climate? Not yet

Faster disaster: climate change fuels ‘flash droughts’, intense downpours and storms

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Andrew King, The University of Melbourne and Andrew Dowdy, The University of Melbourne

The run of extreme weather events around the world seems to be never-ending. After the northern summer of extreme heat and disastrous fires, we’ve seen more exceptional autumn weather over Europe with record-breaking heat in the UK.

Meanwhile, record-breaking rain and intense flash floods struck Greece before the same storm devastated Libya, with thousands dead.

Almost 20% of Africa is estimated to be in drought, and drought conditions are returning to parts of Australia. To top it off, we’ve seen several hurricanes intensify unusually quickly in the Atlantic.

We know climate change underpins some of the more extreme weather we’re seeing. But is it also pushing these extreme events to happen faster?

The answer? Generally, yes. Here’s how.

Flash droughts

We usually think of droughts as slowly evolving extreme events which take months to form.

But that’s no longer a given. We’ve seen some recent droughts develop unexpectedly quickly, giving rise to the phrase “flash drought”.

How does this happen? It’s when a lack of rainfall in a region combines with high temperatures and sunny conditions with low humidity. When these conditions are in place, it increases how much moisture the atmosphere is trying to pull from the land through evaporation. The end result: faster drying-out of the ground.

Flash droughts tend to be short, so they don’t tend to cause the major water shortages or dry river beds we’ve seen during long droughts in parts of Australia and South Africa, for example. But they can cause real problems for farmers. Farmers in parts of eastern Australia are already grappling with the sudden return of drought after three years of rainy La Niña conditions.

As we continue to warm the planet, we’ll see more flash droughts and more intense ones. That’s because dry conditions will more often coincide with higher temperatures as relative humidity falls across many land regions.

Flash floods and extreme rainfall

Climate change can cause increased rainfall variability. Some parts of the world will get a lot wetter, on average, while others will get drier, increasing the variation in rainfall between different regions. For Australia, most locations are generally expected to have intensified downpours of rain, as well as intensified droughts. So we might be saying more often “it doesn’t rain, it pours!”.

We’re seeing exceptionally extreme rainfall in many recent events. The recent floods that submerged villages in Greece came from a sudden downpour of over 500 millimetres in a single day. Hong Kong was hit last week by the heaviest rains in 140 years, flooding subway stations and turning streets into rivers.

But why does it happen so quickly?

Sudden extreme rains fall when we have very moist air coupled with a weather system that forces air to rise.

We’ve long known human-caused climate change is increasing how much moisture the air can hold generally, rising by about 7% per degree of global warming. That means storms now have the potential to hold and dump more water.

Notably, the impact of climate change on rain-bearing weather systems can vary by region, which makes the picture more complicated. That means, for instance, climate change may lead to more extreme rain in some places, while other places may only see an intensification in really short extreme rain events and not for longer timescales.

We can safely say, though, that in most parts of the world, we’re seeing more intense storms and sudden extreme rainfall. Sudden dumps of rain drive flash floods.

More moisture in the air helps fuel more intense convection, where warm air masses rise and form clouds. In turn, this can trigger efficient, quick and intense dumps of rain from thunderstorms.

These short-duration rain events can be much larger than you’d expect from the 7% increase in moisture per degree of warming.

Flash cyclones? Hurricanes are intensifying faster

Last month, Hurricane Idalia caused major flooding in Florida. As we write, Hurricane Lee is approaching the US.

Both tropical storms had something odd about them – unusually rapid intensification. That is, they got much stronger in a short period of time.

Usually, this process might increase wind speeds by about 50 kilometres per hour over a 24-hour period for a hurricane – also known as tropical cyclones and typhoons. But Lee’s wind speeds increased by 129km/h over that period. US meteorological expert Marshall Shepherd has dubbed the phenomenon “hyperintensification”, which could put major population centres at risk.

Rapidly intensifying tropical cyclones are strong and can be very hazardous, but they aren’t very common. To trigger them, you need a combination of very high sea surface temperatures, moist air and wind speeds that don’t change much with height.

While still uncommon, rapid intensification is potentially getting more frequent as we heat the planet. This is because oceans have taken up so much of the heat and there’s more moisture in the air. There’s much more still to learn here.

Australia’s El Niño summer in a warming world

Spring and summer in Australia are likely to be warmer and drier than usual. This is due to the El Niño climate cycle predicted for the Pacific Ocean. If, as predicted, we also get a positive Indian Ocean Dipole event, this can heighten the hotter, drier weather brought by El Niño. After three wet La Niña years, this is likely to be a marked shift.

If it arrives as expected, El Niño would lower the risk of tropical cyclones for northern Australia and reduce chances of heavy rain across most of the continent.

But for farmers, it may help trigger flash droughts. Prevailing warm and dry conditions may rapidly dry the land and reduce crop yields and slow livestock growth.

Drier surfaces coupled with grass growth from the wet years could worsen fire risk. Grass can dry out much faster than shrubs or trees, and grass fires can start and spread very rapidly.

Climate change loads the dice for extreme weather. And as we’re now seeing, these extremes aren’t just more intense – they can happen remarkably fast. The Conversation

Andrew King, Senior Lecturer in Climate Science, The University of Melbourne and Andrew Dowdy, Principal Research Scientist, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingFaster disaster: climate change fuels ‘flash droughts’, intense downpours and storms

Summer 2023 was the hottest on record – yes, it’s climate change, but don’t call it ‘the new normal’

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Kansas City’s baseball stadium ran misters to cool people off in heat near 100 degrees on June 28, 2023.
AP Photo/Charlie Riedel

Scott Denning, Colorado State University

Summer 2023 has been the hottest on record by a huge margin. Hundreds of millions of people suffered as heat waves cooked Europe, Japan, Texas and the Southwestern U.S. Phoenix hit 110 degrees Fahrenheit (43 degrees Celsius) for a record 54 days, including a 31-day streak in July. Large parts of Canada were on fire. Lahaina, Hawaii, burned to the ground.

As an atmospheric scientist, I get asked at least once a week if the wild weather we’ve been having is “caused” by climate change. This question reflects a misunderstanding of the difference between weather and climate.

Consider this analogy from the world of sports: Suppose a baseball player is having a great season, and his batting average is twice what it was last year. If he hits a ball out of the park on Tuesday, we don’t ask whether he got that hit because his batting average has risen. His average has gone up because of the hits, not the other way around. Perhaps the Tuesday homer resulted from a fat pitch, or the wind breaking just right, or because he was well rested that day. But if his batting average has doubled since last season, we might reasonably ask if he’s on steroids.

Unprecedented heat and downpours and drought and wildfires aren’t “caused by climate change” – they are climate change.

The rise in frequency and intensity of extreme events is by definition a change in the climate, just as an increase in the frequency of base hits causes a better’s average to rise.

And as in the baseball analogy, we should ask tough questions about the underlying cause. While El Niño is a contributor to the extreme heat this year, that warm event has only just begun. The steroids fueling extreme weather are the heat-trapping gases from burning coal, oil and gas for energy around the world.

Nothing ‘normal’ about it

A lot of commentary uses the framing of a “new normal,” as if our climate has undergone a step change to a new state. This is deeply misleading and downplays the danger. The unspoken implication of “new normal” is that the change is past and we can adjust to it as we did to the “old normal.”

Unfortunately, warming won’t stop this year or next. The changes will get worse until we stop putting more carbon dioxide and other greenhouse gases into the atmosphere than the planet can remove.

The excess carbon dioxide humans have put into the atmosphere raises the temperature – permanently, as far as human history is concerned. Carbon dioxide lingers in the atmosphere for a long time, so long that the carbon dioxide from a gallon of gasoline I burn today will still be warming the climate in thousands of years.

That warming increases evaporation from the planet’s surface, putting more moisture into the atmosphere to fall as rain and snow. Locally intense rainfall has more water vapor to work with in a warmer world, so big storms drop more rain, causing dangerous floods and mudslides like the ones we saw in Vermont, California, India and other places around the world this year.

By the same token, anybody who’s ever watered the lawn or a garden knows that in hot weather, plants and soils need more water. A hotter world also has more droughts and drying that can lead to wildfires.

So, what can we do about it?

Not every kind of bad weather is associated with burning carbon. There’s scant evidence that hailstorms or tornadoes or blizzards are on the increase, for example. But if summer 2023 shows us anything, it’s that the extremes that are caused by fossil fuels are uncomfortable at best and often dangerous.

Without drastic emission cuts, the direct cost of flooding has been projected to rise to more than US$14 trillion per year by the end of the century and sea-level rise to produce billions of refugees. By one estimate, unmitigated climate change could reduce per capita income by nearly a quarter by the end of the century globally and even more in the Global South if future adaptation is similar to what it’s been in the past. The potential social and political consequences of economic collapse on such a scale are incalculable.

Fortunately, it’s quite clear how to stop making the problem worse: Re-engineer the world economy so that it no longer runs on carbon combustion. This is a big ask, for sure, but there are affordable alternatives.

Clean energy is already cheaper than old-fashioned combustion in most of the world. Solar and wind power are now about half the price of coal- and gas-fired power. New methods for transmitting and storing power and balancing supply and demand to eliminate the need for fossil fuel electricity generation are coming online around the world.

In 2022, taxpayers spent about $7 trillion subsidizing oil and gas purchases and paying for damage they caused. All that money can go to better uses. For example, the International Energy Agency has estimated the world would need to spend about $4 trillion a year by 2030 on clean energy to cut global emissions to net zero by midcentury, considered necessary to keep global warming in check.

Just as the summer of 2023 was among the hottest in thousands of years, 2024 will likely be hotter still. El Niño is strengthening, and this weather phenomenon has a history of heating up the planet. We will probably look back at recent years as among the coolest of the 21st century.The Conversation

Scott Denning, Professor of Atmospheric Science, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingSummer 2023 was the hottest on record – yes, it’s climate change, but don’t call it ‘the new normal’