Will the weather get worse this year?

Stormy weather. Image: Getty.

Last year unleashed some catastrophic weather across the world. At the beginning of 2017, Australia experienced one of the hottest summers on record in Sydney and Brisbane, followed by a killer summer heatwave across southern Europe and wildfires triggered by heat in California.

The Atlantic hurricane season was particularly active, recording three mighty category 5 hurricanes – Harvey, Irma and Maria – resulting in significant casualties. The cost of the damage across the American continent was in excess of $260bllion.

At the same time, the 2017 monsoon season brought considerable rains to the Indian subcontinent, and resulted in devastating floods in parts of India, Pakistan, Nepal and Bangladesh (one of the most flood vulnerable countries in the world), causing more than 1,000 deaths.

Monsoon flooding in the Himalayan foothills of India, Bangladesh and Nepal affected more than 40m people last year. Image: EPA/creative commons.

At the end of 2017, we could look back at the statistics and see that globally it was the warmest non-El Nino year on record. El-Nino is the warming part of the El-Nino Southern Oscillation (ENSO) cycle which affects global ocean and atmospheric currents and can create powerful storms and hurricanes.

In a world that is getting warmer, what does that mean and what might 2018 hold for weather across the globe? Are we destined to see more and more of these “unusual” and catastrophic weather events which result in significant devastation? What effect will climate change have on our weather and will this become the new norm?

Looking at the facts

First, we need to untangle the difference between weather and climate change, something president Trump seems to confuse. In a nutshell, the difference is time. Weather is the conditions in the atmosphere over a short period of time. Climate is how the atmosphere behaves over a longer period of time. When we talk about climate change, that generally means changes in long-term averages of daily levels of temperature and rainfall. So we may see a change in average or typical weather over a number of years, but we can still experience extremes in any one year.

Source: YouTube/CNN.

Recently, scientists have used robust event attribution where natural or human influences on particular events are studied to understand the role climate change may play in particular weather events. This can help support future regional contingency planning.

This also helps us to understand the role climate change has played in past events such as heatwaves, wildfires, droughts, or extreme flooding and some of their large-scale drivers such as ocean and atmospheric patterns of warming and cooling, like El-Nino.

Looking at the past there are many factors which control the onset, spread and eventual impact of a big weather event. But not all of these factors are climatic and many relate to things such as urbanisation, engineering interventions or land-use changes.

What the future looks like

According to the Intergovernmental Panel on Climate Change IPCC, an international body set up to assess the science of climate change, we can continue to expect an increase in the average global temperature. That means we will be experiencing warmer years in the future.

But at the same time, we may see changes to the extremes, which could become more frequent in the case of high temperature or heavy rainfall, or less frequent in the case of extreme cold. This means that the distribution, occurrence and expected averages of our weather (for example, temperature and rain) throughout the year may change, resulting in warmer years on average with more extreme hot days, and fewer extreme cold days in the future.

Heavy snowfall on the US eastern seaboard seriously disrupted cities like New York this winter. Image: EPA/creative commons.

This pattern has a direct link to such phenomena as heatwaves, which are caused by more extreme temperatures. The links to droughts or periods of extreme low flows in rivers are more complex. Global Circulation Models (GCMs) – a collection of numerical models that provide a 3D analysis of global climate interactions such as atmosphere, oceans, ice and land – predict increases in temperatures for some regions, such as southern Europe.

In terms of tropical cyclones, the effects of climate change on these phenomena is an active area of research as the processes are complex. For example, the Clausius-Clapeyron relationship which can be related to the water vapour-carrying capacity of the atmosphere, may have an impact on the strength and intensity of such storms.


The relationship states that for every degree rise in temperature, the water-holding capacity of the atmosphere increases by 7 per cent, so in a warming ocean, the air above the water has a much greater capacity to hold water and thus store more rain that can feed more powerful storms.

But sinking cold air from the upper atmosphere may prevent storms from rising in the first place. If this happens more frequently with climate change then we can expect fewer such storms. That means in the future there may be fewer tropical cyclones forming, but those that do will be stronger and more intense.

Wet wet wet

In a warming world, we can expect it to get wetter. The distribution of the rainfall throughout the year could change as we experience longer, drier spells, although when rain falls it may be in intense bursts. Recent research by Newcastle University analysed the results from finer scale GCMs climate projections and suggests we may expect more intense summer rainfall in the UK in future. New climate projections from GCMs are being prepared for the UK to help predict what the future climate may look like.

Flooding from intense rainfall or river sources has many complex drivers which cause the damage in catchment areas. For example, land use changes (such as intensive farming practices or deforestation) and the degree of urbanisation both play a part in flood risk. Recent research for the UK suggests that we will see an increase in the frequency of extreme river flooding.

Source: KSBY News/YouTube.

So what can we expect for 2018? Already Australia is experiencing extreme heat, while the eastern seaboard of the US is suffering a severe cold spell, and the west coast devastating mudslides that have killed 17 people. So far 2018 seems to be picking up right where 2017 left off.

The ConversationGovernments need to recognise and absorb that extreme weather across the globe is likely to become more common and start to adapt accordingly, rather than treat it as shocking one-off events. Otherwise, we risk increasing loss of life and environmental damage in the future.

Lindsay Beevers, Professor/Chair Futures Forum, Heriot-Watt University.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Air pollution in London is now so bad it’s affecting lung development

Cough, splutter. Image: Getty.

Air pollution is known to contribute to early deaths from respiratory and cardiovascular disease. There is also mounting evidence to show that breathing polluted air increases the risk of dementia. Children are vulnerable, too: exposure to air pollution has been associated with babies being born underweight, as well as poorer cognitive development and lung function during childhood.

Cities including London are looking to tackle the social, economic and environmental costs of air pollution by improving urban air quality using low emission zones. In these zones, the most polluting vehicles are restricted from entering, or drivers are penalised to encourage them to take up lower emission technologies. London’s low emission zone was rolled out in four stages from February 2008 to January 2012, affecting mainly heavy and light goods vehicles, such as delivery trucks and vans.

But our new research, involving more than 2,000 children in four of London’s inner-city boroughs, reveals that while these measures are beginning to improve air quality, they do not yet protect children from the harmful effects of air pollution. It is the most detailed assessment of how a low emission zone has performed to date.

Young lungs

Our study focused mainly on the boroughs of Tower Hamlets and Hackney, but also included primary schools in the City of London and Greenwich. All of these areas experienced high levels of air pollution from traffic, and exceeded the annual EU limit for nitrogen dioxide (NO₂). What’s more, they have a very young demographic and are among the UK’s most deprived areas.

Between 2008-9 and 2013-14, we measured changes to air pollution concentrations in London, while also conducting a detailed examination of children’s lung function and respiratory symptoms in these areas.

Every year for five years, we measured the lung function in separate groups of 400 children, aged eight to nine years old. We then considered these measurements alongside the children’s estimated exposure to air pollution, which took into account where they lived, and the periods they spent at home and at school.

Our findings confirmed that long-term exposure to urban air pollution is related to smaller lung volumes among children. The average exposure for all children over the five years of our study was 40.7 micrograms of NO₂ per cubic metre of air, which was equivalent to a reduction in lung volume of approximately 5 per cent.

Changes of this magnitude would not be of immediate clinical significance; the children would be unaware of them and they would not affect their daily lives. But our results show that children’s lungs are not developing as well as they could. This is important, because failure to attain optimal lung growth by adulthood often leads to poor health in later life.

Over the course of the study, we also observed some evidence of a reduction in rhinitis (a constant runny nose). But we found no reduction in asthma symptoms, nor in the proportion of children with underdeveloped lungs.


Air pollution falls

While the introduction of the low emission zone did relatively little to improve children’s respiratory health, we did find positive signs that it was beginning to reduce pollution. Using data from the London Air Quality Network – which monitors air pollution – we detected small reductions in concentrations of NO₂, although overall levels of the pollutant remained very high in the areas we looked at.

The maximum reduction in NO₂ concentrations we detected amounted to seven micrograms per cubic metre over the five years of our study, or roughly 1.4 micrograms per cubic metre each year. For context, the EU limit for NO₂ concentrations is 40 micrograms per cubic metre. Background levels of NO₂ for inner city London, where our study was located, decreased from 50 micrograms to 45 micrograms per cubic metre, over five years. NO₂ concentrations by the roadside experienced a greater reduction, from 75 micrograms to 68 micrograms per cubic metre, over the course of our study.

By the end of our study in 2013-14, large areas of central London still weren’t compliant with EU air quality standards – and won’t be for some time at this rate of change.

We didn’t detect significant reductions in the level of particulate matter over the course of our study. But this could be because a much larger proportion of particulate matter pollution comes from tyre and brake wear, rather than tail pipe emissions, as well as other sources, so small changes due to the low emission zone would have been hard to quantify.

The route forward

Evidence from elsewhere shows that improving air quality can help ensure children’s lungs develop normally. In California, the long-running Children’s Health Study found that driving down pollution does reduce the proportion of children with clinically small lungs – though it’s pertinent to note that NO₂ concentrations in their study in the mid-1990s were already lower than those in London today.

Our findings should encourage local and national governments to take more ambitious actions to improve air quality, and ultimately public health. The ultra-low emission zone, which will be introduced in central London on 8 April 2019, seems a positive move towards this end.

The scheme, which will be expanded to the boundaries set by the North and South circular roads in October 2021, targets most vehicles in London – not just a small fraction of the fleet. The low emission zone seems to be the right treatment – now it’s time to increase the dose.

The Conversation

Ian Mudway, Lecturer in Respiratory Toxicology, King's College London and Chris Griffiths, Professor of Primary Care, Queen Mary University of London.

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