Advanced science, Environmental, International, Technical

Solar radiation management can help combat climate change

In the Environmental Physics course that I teach from time to time, a student once remarked that we really do not have to worry about the deleterious effects of climate change because technology would be able to solve all the problems we are facing. At that time, I thought this viewpoint is an extreme case of technological optimism. But today, as the likelihood of international consensus to stabilise atmospheric composition of greenhouse gases seems remote while the consequences of climate change are becoming more apparent and direr, many in the scientific community believe that the potential last-ditch effort to stave off the disastrous impacts of climate change is to appeal to technology, geoengineering in particular. Even the United Nation’s Intergovernmental Panel on Climate Change considers geoengineering as a necessary Plan B if global warming does not show any signs of slowing.

Geoengineering is deliberate, large-scale manipulation of the Earth’s environment to counteract anthropogenic climate change. It encompasses two different approaches using a variety of cutting-edge technologies to undo the effects of greenhouse gas emissions. They are removal and sequestration of carbon dioxide to lower its concentration in the atmosphere and offsetting global warming by targeting the overall amount of solar energy reaching the Earth. The removal technologies were discussed in an op-ed piece published in this newspaper on November 29, 2018.

Some of the offsetting options scientists are exploring are reflecting part of the sunlight back into space before it reaches the Earth’s surface, allowing more of the heat trapped by the Earth’s surface to escape into space, and increasing the reflectivity of roofs, Arctic ice, glaciers, pavements, croplands and deserts. Known as Solar Radiation Management (SRM), these options would slow down the rise in Earth’s temperature until carbon dioxide emissions can be reduced enough to prevent catastrophic repercussions of human-driven climate change.

The fraction of incoming sunlight that is reflected back to space could readily be changed by increasing the reflectivity of the low-level clouds. This could be achieved by spraying seawater in the air where they would evaporate to form sea salt, which would seed the clouds above the oceans making them thicker and more reflective. Several simulations have confirmed that the seeding mechanism, also known as Marine Cloud Brightening, would work with the likelihood to lower temperatures at a regional level.

Another proposed cloud-based approach involves thinning the high-altitude Cirrus clouds in the stratosphere by injecting ice nuclei into regions where the clouds are formed. These wispy clouds do not reflect much solar radiation back into space, and instead trap heat in the atmosphere by absorbing thermal radiation emitted by the Earth. While this method is not technically an example of SRM, thinning Cirrus clouds would provide more pathways for the trapped heat to escape into space, and thus, potentially cool the Earth. Currently, work in this field is limited to theoretical studies at research institutions. However, research shows that a cooling of about one degree Celsius is possible by thinning the clouds globally.

Scientists have known for a long time that volcanic eruptions could alter a planet’s climate for months on end, as millions of sunlight-reflecting minute particles (aerosols) are spread throughout the atmosphere. Indeed, the “cold and miserable” summer of 1816 in China, Europe and North America is attributed to the enormous eruption of the Indonesian volcano Tambora in 1815. Though the aerosol haze produced by the Tambora eruption reflected less than one percent of sunlight, it was enough to drop global temperatures by as much as two degrees by the summer of 1816.

The 1991 explosion of Mount Pinatubo in the Philippines cooled the Earth by about 0.5 degrees, while the average global temperatures were as much as one degree cooler for the next five years after the 1883 eruption of Krakatoa in Indonesia. Furthermore, the volcanic-induced cooling of the oceans caused by Krakatoa’s eruption was enough to offset rise in the ocean temperature and sea level for a few decades.

Inspired by these eruptions and the subsequent cooling effect of their sunlight-blocking plume of sulphate particles, scientists are suggesting injecting sulphate aerosols or hydrogen sulphide in the stratosphere. The geoengineering research programme at Harvard University is currently trying to model how clouds of such particles would behave.

One of the more practical SRM techniques that can be implemented easily is whitening surfaces like roofs, croplands and pavements to reflect more sunlight back into space. By absorbing less sunlight, they would negate some of the warming effect from greenhouse gas emissions. This is what greenhouse owners do with whitewash and blinds.

The small island of Bermuda in the North Atlantic is leading the way with white roof houses that not only reflect sunlight, but also keep the homes cooler during the hotter months. A study at the Lawrence Berkeley National Laboratory in California indicates that a 1,000 square foot of white rooftop has about the same one-time impact on global warming as reducing ten tons of carbon dioxide emissions.

Ice sheets are responsible for reflecting lots of sunlight into space. So less ice in the Arctic due to melting means less heat leaving the planet. Hence, scientists want to spread tiny glass beads around the Arctic in the hopes of making the polar ice more reflective and less prone to melting. Another idea is to cover deserts and glaciers with reflective sheets.

Perhaps the most challenging concept to control solar radiation entails deploying an array of reflecting mirrors at strategic points between the Sun and the Earth—just as we all do with sunscreens and sunblocks. Calculations by space scientists at the Lawrence Livermore National Laboratory in California indicate that a mirror roughly the size of Greenland would be able to block one to two percent of solar radiation from reaching the Earth. The idea of a sunscreen is still on the drawing board.

Finally, as we transition into a new era in which human activity is shaping the Earth more than the natural forces, technology could be seen as a way of humans reshaping the planet by limiting the adverse effects of climate change. Also, because international political efforts to curtail greenhouse gas emissions have been slow in coming, solar radiation management is a possible measure to be used if climate change trends become disruptive enough to warrant extreme and risky measures.

Quamrul Haider is a professor of physics at Fordham University, New York.

Advanced science, Bangladesh, Environmental, International, Life as it is, Political, Technical

We are hurtling towards a disastrous Climate Change (Part II)

In Part I, it was shown unambiguously that human activities from the period of industrial revolution (1720 – 1800) had been the root cause for the rise of global temperature by over 1ºC due to emission of greenhouse gases into the atmosphere. As industrial activities became more and more widespread, the greenhouse gas emission and its accumulation in atmosphere increased correspondingly and the global temperature went up even higher.

Climatologists, Geoscientists, Atmospheric Scientists and so forth had been warning the world leaders of signs of increase in global temperature over and above the natural increase right from the early 1970s. As time passed, their warning became louder and louder, but the leaders of industrialised countries deliberately ignored them or rejected their scientific evidence. United States of America is, in particular, the champion of such denial right from the beginning – presidents like Ronald Reagan, George H W Bush, George W Bush and recently Donald Trump are all rejectionists of man-made global climate change.

Despite incontrovertible scientific principle and evidence that increase in carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbon (CFC) and other gases in atmosphere traps energy i.e. heat within earth’s atmosphere and thereby increase global temperature, the deniers reject all these arguments. Their short-sightedness and the damage they are inflicting on Earth are simply inexcusable.

The consequences of global increase in temperature are given below:

When air temperature increases, land surface temperature increases more than the sea temperature, as heat capacity of water is more than that of soil. What it means is that for the same amount of heat, water temperature will increase less (due to its high heat absorbing capacity) than that of soil. Similarly, when air temperature drops, land temperature drop would be more than sea temperature. Thus, sea temperature does not move up or down as much as the adjoining land mass temperature and that is why we get the moderating effect of sea.

This land-sea temperature differential is also the cause of rain, storm, snowfall etc. In the summer, land temperature increases substantially causing air to rise to high altitude and sea air being relatively cooler and heavier but laden with moisture moves towards land and gives rain. A higher temperature difference would give higher amount of rain, higher wind velocity (storm, tornado etc). Reciprocally, in the winter there would be severe snowfall, extreme cold spell etc. So, the climate change would exacerbate the nascent conditions.   

Melting of inland glaciers around the world, which would then be followed by Antarctic and Greenland ice sheets melting would cause sea-level to rise significantly. It is not only the extra volume of water from melting ice but also the thermal expansion of water due to rise in temperature that would cause sea-levels to rise and inundate large areas of land mass. It is estimated by the Inter-governmental panel on Climate Change (IPCC) that by the end of this century, the sea-level is likely to rise by at least 6ft (or even higher), if no remedial action is taken now i.e. if life continues as ‘business-as-usual’. But if action is taken urgently now to limit temperature rise to 1.50C, the sea-level rise may be contained within 3ft to 6ft.

Figure 1. Mangrove areas of Sundarbans in Bangladesh at present

In addition to that, worsening storm surge, frequent tropical storm and concentrated rainfall will affect large coastal areas and even inlands of a country, islands and low-lying areas. Bangladesh, a low-lying country, would be badly affected by sea-level rise. The average landmass there is only about 5ft above the sea level. Figure 1 shows the mangrove areas of Sundarbans in the southern part of the country at present and Figure 2 when sea level rises by the smallest estimated margin of about 3ft.  It can be seen that large areas have been inundated by the rising sea level. It is estimated that 1.3 billion people world-wide would be affected, which may require their permanent relocation or even mass migration.

Figure 2. Mangrove areas of Sundarbans in Bangladesh anticipated to be around 2050 AD.

It may be pointed out that sea-level rise does not just cause submersion of landmass, which might have been habitable area previously, but also damages arable land. Ingress of saline water precludes cultivation of crops, vegetation etc even in surrounding areas which are not inundated. 

Thawing permafrost speed up global warming, as permafrost is basically soil that stays below freezing (00C) for at least two years. Plants capture carbon dioxide (CO2) from the atmosphere by photosynthesis process and then this carbon is released when wood (in roots) decays in the soil or carbon is compressed in the natural process to form coal. In Arctic areas, wood decay or decomposition is very slow and hence these areas are regarded as carbon sink. However, decomposition increases as temperature increases causing enhanced carbon emission. The inventory of frozen carbon in permafrost is 1.5 trillion tons, which is nearly twice the amount of carbon in the atmosphere now!

Wildfires are caused due to global warming and these then contribute to further global warming. Wildfire thus has a positive (destructive) feedback effect. Trees and vegetation absorb CO2 and convert it to oxygen (O2), thus acting as sinks. Tropical forests in Indonesia, Malaysia, Brazil and in other parts of the world play a vital role in carbon sequestration. However, wildfires effectively convert the sink of carbon straight into source of carbon! The forest fires that are razing in the Amazon rain forest now, which is regarded as the lungs of the planet Earth, are extremely damaging. These forest fires are not natural wildfires; these are deliberate man-made fires to clear forest areas for agricultural use (deforestation). Man is making the planet uninhabitable. 

The effect of all these changes is causing severe disruption to the climate. Where there were moderate rainfalls, now there are severe rainfalls causing flash flood, bursting of dams, landslides etc. In 2018, there were devastating floods in Japan, North Korea and India. In 2019, bridges in North Yorkshire, England collapsed when full month’s rain fell in just four hours.

While some parts of the world were having tremendous amount of rainfall in short spell of time, others were baking in heat waves. France’s capital Paris experienced this summer (June 2019) the highest temperature of 46ºC and India experienced 50ºC. Pakistan experienced a deadly heat wave where highest recorded temperature was 54ºC!

There were unprecedented wildfires in Greece and Australia. Wildfires in the forest area called Paradise in California are devastating and becoming a regular event. Northern Finland (in Arctic Circle) and Siberia were used to be considered so cold that wildfires were thought to be incredible, but not anymore. Last year as well as this year, wildfires in those areas devastated large land mass.

In the year 2017, hurricane Irna, a category 5 storm, was the most powerful Atlantic storm in a decade to strike the Caribbean and Southern US. In addition, hurricane Harvey in Texas and hurricane Maria in Dominican Republic wrought havoc. Monsoon floods in Bangladesh and mudslides in Sierra Leone are devastating natural disasters in 2017.

The frequency and severity of these natural disasters are breaking all previous records. A natural disaster, which only 10 or 15 years ago would have been considered once in 100 years event, is now happening once or twice a decade and if runaway conditions are allowed to continue, those events may become regular events!

Donald Trump not only denies man-made climate change but also encourages activities which cause climate change. He and his right-wing coterie of extremist Republicans in America hold and promote the view that climate change is due to natural phenomenon. There is an Institute in America, called the Heartland Institute (which Trump endorses and supports) which claims to be one of the world’s “leading free market think-tanks” and promotes “free market solutions to social, economic and environmental problems”. It disputes scientific observations and knowledge on climate change (as is usual with right-wing cliques to denigrate scientific knowledge), criticises climate mitigation activities and promotes use of fossil fuels. 

When confronted with increased severity and more frequent incidences of droughts, forest and bush fires, floods, storms, tropical cyclones, cold spells etc, these climate change deniers assert these are just natural phenomena; nothing to do with human activities. Their denial is either based on sheer ignorance or moral depravity.

Dr A Rahman is an author and a columnist


Environmental, International, Life as it is, Political

Do world leaders understand the consequences of the climate crisis?

School children playing on melting ice in Yukon Delta in Alaska

Since the Industrial Revolution, we have created a hodgepodge of human systems that are at odds with natural systems that support them. In the process, we are pushing billions of people into a dystopian future by bequeathing them with a climate crisis.

While schoolchildren worldwide are on the streets protesting government inaction and millions are displaced by climate-induced disasters, the laissez-faire attitude of our leaders, save a few, sends the message that the current upward trajectory of the crisis does not seem to be a pressing problem. Instead, those who resist the powerful that are savaging our ecosystems and driving people off their land face death and fear, according to the latest annual report from Global Witness.

At various conventions and Conference of Parties (COP), discussions on climate change resemble the tale of a group of blind men touching various parts of an elephant, each arriving at a very different conclusion of what it is like. To one it is like a tree, to another a snake, to a third a wall, to the fourth a spear, so on and so forth. A wise man tells the group that an elephant has all the features they mentioned, but they are missing the big picture. The moral of the parable is that we have a tendency to project our partial experiences as the whole truth, contrary to what reality is. Thus, just like the blind men, politicians and world leaders are missing the “big picture” of human-induced climate change.

Scientists have been warning since the 1980s that to limit the most damaging impacts of climate change, strong policies are needed to limit greenhouse gas emissions. Ignoring their warnings, politicians allowed greenhouse gases to build up to potentially dangerous levels in the atmosphere. The reason: most likely their lack of knowledge about climatology—a multidisciplinary subject requiring insights from astronomy, biology, botany, chemistry, cosmology, economics, geology, history, oceanography, palaeontology, physics and statistics, among other disciplines. One wonders, how many of them or their advisors have mastery of more than one or two of these disciplines.

Eventually, in 1988, the Intergovernmental Panel on Climate Change (IPCC) was formed by the United Nations Environmental Programme and World Meteorological Organization to play a leadership role in tackling climate change. That said, instead of setting the agenda on global climate, IPCC has become a political body controlled by a few powerful nations that are also the biggest emitters of greenhouse gases. Other nations that claim to be victims of climate change, yet emit carbon dioxide in copious amounts or build coal-fired power plants near huge carbon sinks or open up rainforests for mining, are third world and developing countries lacking a government strong enough to enforce any measures.

Failing to find a one-size-fits-all solution to counter climate change has prompted IPCC to water down the global climate target in the hope of getting some sort of an agreement. Consequently, it is no longer pushing for binding commitments to reduce emissions, whether for developed or for developing countries. Furthermore, the widely publicised pledge of giving developing countries billions of dollars to cope with the effects of climate change is essentially relabelling foreign aid already going to those countries. Besides, in countries where corruption is endemic, how much of the money, though laughably inadequate, is used for adaptation is questionable.

One could argue that the 2015 Paris Climate Agreement hammered out at COP21 was the first step towards solving the problems resulting from climate change. Regrettably, that first step has so far been Captain Ahab’s “Moby Dick”, the elusive white whale. Hence, there are ample reasons to believe that the agreement is not going to effect any meaningful change in global warming.

So far this year, more than dozen conferences and symposia on global climate change were held in different countries. These conferences, including COP24 last year, dealt with adaptation measures only, which are needed to respond to climate change that has already occurred. However, are there any plan(s) for the future when our planet might become close to uninhabitable? Can we expect an answer from the “political climate pundits” when they will meet in New York and Santiago (Chile) later this year?

While we are waiting for an answer, global emissions of carbon dioxide are at a record high, with no signs of slowing. The atmosphere is warming, glaciers are melting, permafrost is thawing and seas are rising. Extreme weather is bringing floods, storms, droughts and other disasters to every region of the world. Moreover, climate change is creating problems in almost every aspect of our life, from public health to food security, from water availability to the economy, and much more.

If greenhouse gas emissions continue to rise unchecked, repercussions of climate change are going to be profound in the future. They would destabilise governments, produce waves of refugees, flood most of the world’s coastal cities and most importantly would make continuing degradation of the Earth irreversible.

Clearly, because of inaction by our leaders, we will be handing over to our future generations a planet that will be close to unliveable. As for themselves and their descendants, they would probably buy their way out of the worst effects of climate change while the rest of us drown or choke to death. This is “climate apartheid,” already practised by the perversely wealthy and powerful.

Today, we are seemingly transitioning to a new geologic epoch, Holocene to Anthropocene, where the climate is very different from the one our ancestors knew. Confronting realities of the new epoch requires courage which many of our leaders lack. Also, their myopic vision does not allow them to think beyond the next election. In fact, a group called Extinction Rebellion claims that their failure in addressing the climate crisis makes them guilty of “criminal inactivity.” It is, therefore, obvious that to keep our planet inhabitable, we need leaders with fortitude, wisdom and acumen, leaders who are not beholden to “corporations financing the injustice of climate change,” and more importantly leaders with vision to guide us through what, by all accounts, will be some challenging decades ahead.

Suffice it to say, should we falter in dealing with the challenges of climate change head-on, not only will the universal goal of peace and happiness for humankind slip out of our grasp, but man’s struggle for mere survival will also be jeopardised.

Quamrul Haider is a Professor of Physics at Fordham University, New York.