Climate change Impact & implications

Once upon a not-so-distant time, places experienced four conventional seasons — spring, summer, autumn (Fall) and winter. However, scientists have discovered that as the planet warms up, the tropics have been expanding by 0.1 to 0.2 degrees of latitude every decade as a result of which regions that once had four seasons are shifting to having just two.

But even in regions with four seasons, weather and temperature patterns have been altered. Across the United States, the shift from cold weather in the winter to warm spring temperatures happens earlier now than it did in the past, and the period of winter weather is shorter and generally milder.

Even the heatwaves are starting later in the summer months. An extended period of record-breaking heat struck the central United States in late August 2023, with the worst conditions occurring on August 23 and 24 in northern Illinois and northwest Indiana.

This marked the first time since a July 1995 heatwave that Chicago experienced consecutive days with heat indices exceeding 115 degrees Fahrenheit (46 degrees Celsius).

There is one analysis that suggests summers are now 13 days longer and winters are 20 days shorter than they used to be.

Parts of the United States’ eastern seaboard have been hit with massive floods this year, a phenomenon that’s expected to grow more common — and worse.

“It’s worse than a new normal. I call it a new abnormal,” University of Pennsylvania climate scientist Michael Mann was quoted as saying.

New York City experienced intense rains that left parts of the city underwater. Over the summer, the Philadelphia suburbs were hit with heavy flash flooding that inundated roads and killed five people. Earlier this year, Vermont also experienced heavy flooding that trapped people in their homes and damaged roads and buildings. Nationally, tens of millions of people were under a flood watch in July, while globally, countries including South Korea, Pakistan, India and Turkey have seen destructive flooding that has displaced millions of people and forced evacuations in the last year.

“Everywhere is susceptible to these impacts,” Mann was quoted as saying. “The western, central, and eastern US, Europe, and Asia — with one of the best examples being the Pakistan floods last year which displaced more than 30 million people.”

As the Earth gets warmer, the atmosphere is able to hold more water, leading to heavier precipitation when it rains, and a greater likelihood of flooding as a result. A 1 degree centigrade increase in the atmosphere’s temperature corresponds to a 7 percent increase in water vapour that it’s able to hold, according to the Centre for Climate and Energy Solutions. And estimates suggest global temperatures could breach a 1.5-degree Celsius increase threshold sometime in the 2030s, meaning much more rain to come.

So, what about the factors behind the rise of extreme weather?

Richard Seager of Columbia University believes: “In general, we know that heavy intense precipitation is increasing pretty much everywhere around the world, as a result of rising atmospheric temperatures. There’s never a complete one-to-one relationship between heavy intense precipitation and flooding of rivers. But you could certainly say that heavy, more heavy and intense precipitation is more likely to cause the kinds of flooding that we’ve seen.”

Michael Mann, University of Pennsylvania, says: “Climate change is leading to anomalous warmth around the planet in general, and warmer ocean waters mean more moisture in the atmosphere that is available to produce flooding rains. But climate change is also altering the behaviour of the jet stream, and some of our work suggests that it is leading to a wavier, slower jet stream associated with stalled weather systems that remain stuck in place for days or even weeks on end — that’s when you see the worst flooding events.”

So, is this anomaly the new normal?

Mann explains: “It’s worse than a new normal. I call it a new abnormal, and these flooding events will continue to become more extreme unless we reduce carbon emissions and stop the ongoing heating of the planet.”

Can the increase in severe rain in some places and the rise in droughts in other places be explained?

Seager says: “They are two sides of the same coin. So when the atmosphere can hold more moisture, it also transports more moisture, from one place to the other. So like, in the Southwest United States, where I do most of my work on drought, when there are high-pressure systems… [with] winds blowing out of that area, those are the conditions that set up droughts in those areas. And the atmosphere is extracting moisture from those regions. So when it warms up, [the atmosphere] can hold more moisture, and move more moisture out of those areas. So droughts can intensify. In the warmer atmosphere, you can get both more extreme droughts and you can also get more extreme precipitation and they’re connected by the ability of the atmosphere to hold more moisture and therefore move more moisture from one place to the other, thus creating extremes in both ends of the spectrum.”

Then how effective is forecasting when it comes to predicting severe flood events and warning people?

Daniel Swain, a climate scientist at UCLA Institute of the Environment and Sustainability was quoted as saying: “I mean, absolutely critical. And it’s actually quite good for the most part. If you look at the NOAA predictions for [the floods in the northeastern US], several days in advance, there were [public predictions] that were like, ‘A significant flood event is possible.’ The day before, it was like, ‘We’re highly confident this event will be potentially as bad as what occurred with [Hurricane] Irene, potentially even worse’ — which is exactly what happened. So it’s hard to fault that level of accuracy and the consistency of messaging. I know it still doesn’t mean that everyone gets the message. But that’s not a forecasting problem so much as it is a ... communication and mass messaging problem.”

Recently, a deadly flash flood in the north-east state of Sikkim has shown why India urgently needs to install advanced early warning systems for its dangerous glacial lakes.

At least 70 people, including nine soldiers, died with more than 100 others going missing after South Lhonak, a glacial lake in the Himalayas, burst its banks.

Such outbursts or the sudden release of water from a lake fed by a glacier — can be triggered by heavy rains, earthquakes or avalanches.

An early warning system can help authorities evacuate people in time and open the flood gates from dams downstream to minimise damage.

After the Sikkim disaster, India’s National Disaster Management Authority (NDMA) revealed that in early September it had surveyed two at-risk lakes in order to deploy early warning systems for real-time alerts in the event of glacial lake outbursts. One of them was at South Lhonak, where some work for early warnings was initiated.

So, what is at stake if we don’t limit warming?

* Sea level rise: Rising sea levels could impact one billion people by the year 2050.

* Coral bleaching: Changes in water temperature causes algae to leave coral reefs, turning them white and making them vulnerable to disease and death — a phenomenon known as coral bleaching. Coral bleaching is the first sign of coral death. If too many reefs die, this can lead to the destruction of marine ecosystems and even the extinction of some fish.

* Ice-free Arctic: Arctic sea ice recedes every summer but still covers millions of square miles of ocean today. But the Arctic is warming faster than anywhere else on Earth and ice-free summers could become a reality.

* Heat waves: Heat waves will become more frequent and severe around the world, affecting hundreds of millions — or even billions — of people if immediate action is not taken.

* Flooding: Global warming increases the risk of more frequent—and heavier—rainfall, snowfall, and other precipitation. And as that risk increases, so too does the risk of flooding.

* Destruction of wildlife habitats: As the earth continues to warm, crucial habitats may no longer be hospitable for certain animals or plants. This puts a variety of species at risk, depending on whether they can adapt or move.

It appears that climate change will make some parts of the ocean even noisier, affecting marine life in turn, according to a new study.

Not to forget, you might find 100 per cent of grapes in certain vines getting wiped off while others remain untouched. With increased climate change comes an increase in extreme events. Late frosts, extreme droughts and strong rain and hail during flowering and fruiting are all increasing in frequency in Bordeaux and can wipe out an entire year’s grapes. This means no wine at all from some locations, a potentially wine-changing event.

It’s not just weather that will impact crop yields. As the climate warms and changes, pests and diseases are spreading more widely — adding another layer of unpredictability to farming. Food storage may also become more challenging as rising temperatures make it more likely that insects or mould will destroy crops that are stored outdoors or in protected, but not cooled areas.

The climate crisis is also expected to increase malnutrition by reducing nutrient availability and the quality of food while increasing prices at the same time. Higher temperatures and increased concentrations of CO2 in the air will lead to lower levels of nutrients like iron, zinc and protein in crops like soy, wheat and rice. This issue is especially troubling in countries with less food diversity and where people rely on one or two staple foods for their nutrition.

To put things in perspective, the reality of rapid warming requires that every country create an adaptation strategy to become more resilient to the effects of climate change. Adaptation means lessening the harm caused by storm surges, floods, heat waves, fires and other weather-related perils. It requires new infrastructure, early warning systems and better awareness of how changes in the climate will harm things we value. The best adaptation strategies go further to pursue resilience — the ability to bounce back from destructive changes.

Views expressed are personal