The world may lose half its sandy beaches by 2100. It’s not too late to save most of them



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John Church, UNSW

For many coastal regions, sea-level rise is a looming crisis threatening our coastal society, livelihoods and coastal ecosystems. A new study, published in Nature Climate Change, has reported the world will lose almost half of its valuable sandy beaches by 2100 as the ocean moves landward with rising sea levels.

Sandy beaches comprise about a third of the world’s coastline. And Australia, with nearly 12,000 kilometres at risk, could be hit hard.




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This is the first truly global study to attempt to quantify beach erosion. The results for the highest greenhouse gas emission scenario are alarming, but reducing emissions leads to lower rates of coastal erosion.

Our best hope for the future of the world’s coastlines and for Australia’s iconic beaches is to keep global warming as low as possible by urgently reducing greenhouse gas emissions.

Losing sand in coastal erosion

Two of the largest problems resulting from rising sea levels are coastal erosion and an already-observed increase in the frequency of coastal flooding events.

Erosion during storms can have dramatic consequences, particularly for coastal infrastructure. We saw this in 2016, when wild storms removed sand from beaches and damaged houses in Sydney.

After storms like this, beaches often gradually recover, because sand from deeper waters washes back to the shore over months to years, and in some cases, decades. These dramatic storms and the long-term sand supply make it difficult to identify any beach movement in the recent past from sea-level rise.

What we do know is that the rate of sea-level rise has accelerated. It has increased by half since 1993, and is continuing to accelerate from ongoing greenhouse gas emissions.

If we continue to emit high levels of greenhouse gases, this acceleration will continue through the 21st century and beyond. As a result, the supply of sand may not keep pace with rapidly rising sea levels.

Projections for the worst-case scenario

In the most recent Intergovernmental Panel on Climate Change (IPCC) report, released last year, the highest greenhouse gas emissions scenario resulted in global warming of more than 4°C (relative to pre-industrial temperatures) and a likely range of sea-level rise between 0.6 and 1.1 metres by 2100.

For this scenario, this new study projects a global average landward movement of the coastline in the range of 40 to 250 metres if there were no physical limits to shoreline movement, such as those imposed by sea walls or other coastal infrastructure.




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Sea-level rise is responsible for the vast majority of this beach loss, with faster loss during the latter decades of the 21st century when the rate of rise is larger. And sea levels will continue to rise for centuries, so beach erosion would continue well after 2100.

For southern Australia, the landward movement of the shoreline is projected to be more than 100 metres. This would damage many of Australia’s iconic tourist beaches such as Bondi, Manly and the Gold Coast. The movement in northern Australia is projected to be even larger, but more uncertain because of ongoing historical shoreline trends.

What happens if we mitigate our emissions

The above results are from a worst-case scenario. If greenhouse gas emissions were reduced such that the 2100 global temperature rose by about 2.5°C, instead of more than 4°C, then we’d reduce beach erosion by about a third of what’s projected in this worst-case scenario.

Current global policies would result in about 3°C of global warming.
That’s between the 4°C and the 2.5°C scenarios considered in this beach erosion study, implying our current policies will lead to significant beach erosion, including in Australia.

Mitigating our emissions even further, to achieve the Paris goal of keeping temperature rise to well below 2°C, would be a major step in reducing beach loss.

Why coastal erosion is hard to predict

Projecting sea-level rise and resulting beach erosion are particularly difficult, as both depend on many factors.

For sea level, the major problems are estimating the contribution of melting Antarctic ice flowing into the ocean, how sea level will change on a regional scale, and the amount of global warming.

The beach erosion calculated in this new study depends on several new databases. The databases of recent shoreline movement used to project ongoing natural factors might already be influenced by rising sea levels, possibly leading to an overestimate in the final calculations.




Read more:
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The implications

Regardless of the exact numbers reported in this study, it’s clear we will have to adapt to the beach erosion we can no longer prevent, if we are to continue enjoying our beaches.

This means we need appropriate planning, such as beach nourishment (adding sand to beaches to combat erosion) and other soft and hard engineering solutions. In some cases, we’ll even need to retreat from the coast to allow the beach to migrate landward.

And if we are to continue to enjoy our sandy beaches into the future, we cannot allow ongoing and increasing greenhouse gas emissions. The world needs urgent, significant and sustained global mitigation of greenhouse gas emissions.The Conversation

John Church, Chair Professor, Climate Change Research Centre, UNSW

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

Climate change set to increase air pollution deaths by hundreds of thousands by 2100


Guang Zeng, National Institute of Water and Atmospheric Research and Jason West, University of North Carolina – Chapel Hill

Climate change is set to increase the amount of ground-level ozone and fine particle pollution we breathe, which leads to lung disease, heart conditions, and stroke. Less rain and more heat means this pollution will stay in the air for longer, creating more health problems.

Our research, published in Nature Climate Change, found that if climate change continues unabated, it will cause about 60,000 extra deaths globally each year by 2030, and 260,000 deaths annually by 2100, as a result of the impact of these changes on pollution.

This is the most comprehensive study to date on the effects of climate change on global air quality and health. Researchers from the United States, the United Kingdom, France, Japan and New Zealand between them used nine different global chemistry-climate models.

Most models showed an increase in likely deaths – the clearest signal yet of the harm climate change will do to air quality and human health, adding to the millions of people who die from air pollution every year.


Read more: Can we blame climate change for thunderstorm asthma?


Stagnant air

Climate change fundamentally alters the air currents that move pollution across continents and between the lower and higher layers of the atmosphere. This means that where air becomes more stagnant in a future climate, pollution stays near the ground in higher concentrations.

Ground-level ozone is created when chemical pollution (such as emissions from cars or manufacturing plants) reacts in the presence of sunlight. As climate change makes an area warmer and drier, it will produce more ozone.

Fine particles are a mixture of small solids and liquid droplets suspended in air. Examples include black carbon, organic carbon, soot, smoke and dust. These fine particles, which are known to cause lung diseases, are emitted from industry, transport and residential sources. Less rain means that fine particles stay in the air for longer.

While fine particles and ozone both occur naturally, human activity has increased them substantially.

The Intergovernmental Panel on Climate Change has used four different future climate scenarios, representing optimistic to pessimistic levels of emissions reduction.

In a previous study, we modelled air pollution-related deaths between 2000 and 2100 based on the most pessimistic of these scenarios. This assumes large population growth, modest improvements in emissions-reducing technology, and ineffectual climate change policy.

That earlier study found that while global deaths related to ozone increase in the future, those related to fine particles decrease markedly under this scenario.

Emissions will likely lead to deaths

In our new study, we isolated the effects of climate change on global air pollution, by using emissions from the year 2000 together with simulations of climate for 2030 and 2100.

The projected air pollutant changes due to climate change were then used in a health risk assessment model. That model takes into account population growth, how susceptible a population is to health issues and how that might change over time, and the mortality risk from respiratory and heart diseases and lung cancer.

In simulations with our nine chemistry-climate models, we found that climate change caused 14% of the projected increase in ozone-related mortality by 2100, and offset the projected decrease in deaths related to fine particles by 16%.

Our models show that premature deaths increase in all regions due to climate change, except in Africa, and are greatest in India and East Asia.

Using multiple models makes the results more robust than using a single model. There is some spread of results amongst the nine models used here, with a few models estimating that climate change may decrease air pollution-related deaths. This highlights that results from any study using a single model should be interpreted with caution.

Australia and New Zealand are both relatively unpolluted compared with countries in the Northern Hemisphere. Therefore, both ozone and fine particle pollution currently cause relatively few deaths in both countries. However, we found that under climate change the risk will likely increase.

The ConversationThis paper highlights that climate change will increase human mortality through changes in air pollution. These health impacts add to others that climate change will also cause, including from heat stress, severe storms and the spread of infectious diseases. By impacting air quality, climate change will likely offset the benefits of other measures to improve air quality.

Guang Zeng, Atmospheric Scientist, National Institute of Water and Atmospheric Research and Jason West, Associate Professor, Department of Environmental Sciences and Engineering , University of North Carolina – Chapel Hill

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