Fighting Climate Change
Due to high and rising atmospheric GHG concentrations, the world is poised to experience catastrophic warming, with governments needing to consider potential options for avoiding this fate. The world currently has three main strategies for managing climate risks.
The first is reducing emissions.
The second is carbon dioxide (CO2) removal—or capturing and storing atmospheric carbon through natural or mechanical means.
The third is adaptation—or building resilience to minimize the worst effects of a warming planet.
Unfortunately, at their current paces, both emissions abatement and CDR deployment are occurring far too slowly to avert a dangerous rise in global temperatures. Adaptation—while essential—will nevertheless fail to prevent enormous human misery. Indeed, its limits will become ever more apparent as temperatures rise.
The ultimate solution to the climate emergency is a combination of deep decarbonization and the removal of GHGs from the atmosphere at massive scale. Alas, the world is nowhere near where it needs to be on either front.
As a result of human activity, atmospheric CO2 concentrations have risen from 280 parts per million (ppm) in 1750 to 419 ppm today—higher than at any point in at least the last three million years.
The vast bulk of this increase has occurred since 1960. Even if carbon neutrality is achieved in the coming decades, this accumulated stock of CO2 will remain in the atmosphere for thousands of years, locking in higher global temperatures for the foreseeable future (absent CDR).
In 2015, the parties to the UN Framework Convention on Climate Change (UNFCCC), meeting in Paris, committed to hold the rise in average global temperatures to well below 2°C (3.6°F) and, if possible, to no more than 1.5°C (2.7°F) above preindustrial levels. Today, the world is poised to overshoot both these goals—badly. Humans have reduced the carbon intensity of many economic activities, but overall CO2 emissions have not yet peaked. Last November, as the twenty-sixth Conference of the Parties (COP26) to the UNFCCC began in Glasgow, the UN Environment Program (UNEP) estimated that global emissions would need to decline by 55 percent from 2005 levels by 2030 to meet the 1.5°C Paris goal.
Unfortunately, before the conference, emissions were on track to rise by 16.3 percent, portending a 2.7°C (4.9°F) increase in global temperatures. While new pledges made at Glasgow could— if fully met—limit warming to just 1.8°C (3.2°F), many of these commitments are soft and indeed implausible. Moreover, those projections represent only about 66.7 percent probability outcomes; there remains a one-in-three chance that actual warming levels will be higher even if the world fulfills the Glasgow pledges.
Given the slow pace of emissions abatement, two other strategies to manage climate risk remain. The first is CDR, sucking CO2 directly from the atmosphere and permanently storing it, which can be accomplished using nature-based solutions or negative emissions technologies (NETs). The former seek to enhance the world’s carbon sinks by, for instance, planting trees, cultivating seaweed, increasing the health of agricultural soils, fertilizing the oceans to increase phytoplankton growth, and restoring rain, boreal, and mangrove forests. The latter would encompass building machines to capture atmospheric CO2 and transform it into other compounds or store it permanently underground.
Both forms of CDR face significant obstacles. Implementing the necessary conservation policies and land-use changes for nature-based solutions could require decades of costly adjustments, whereas the risks of climate change are imminent. Similarly, while the pace of NET innovation is quickening, it could take half a century to bring these technologies to scale. Scientists estimate that returning atmospheric CO2 concentrations to preindustrial conditions would entail removing the equivalent of thirty cubic miles of solid black carbon—a volume roughly comparable in size to Mount Rainier and a feat that would presumably dwarf any infrastructure investment ever made.
The remaining currently employed strategy is adaptation, or efforts to anticipate and build resilience against the worst effects of global warming so that humanity can survive the long transition to a postcarbon economy. The coming decades will be ones of planetary upheaval and immense suffering, with more frequent and intense heat waves, storms, droughts, wildfires, sea level rise, and food insecurity. Nations and communities can ameliorate some of these calamities by adopting protective measures such as building seawalls, shifting to droughtresistant agriculture, and greening urban areas. The pace of adaptation can and should accelerate now. Nevertheless, these are essentially palliative measures to reduce—not prevent—pain and misery on a warming planet, the brunt of which will fall heaviest on the most vulnerable populations. Adaptation, moreover, is both astronomically expensive and deeply imperfect. Many nations will lack the capacity and resources to adapt, and numerous climate effects cannot be avoided: they will simply need to be borne.
In short, the world confronts a high-stakes timing predicament.
Although efforts to decarbonize have begun in many countries, global emissions continue to rise. The shift to renewable energy and NETs is happening far too slowly to prevent significant warming by midcentury, and adaptation has its own limitations. In this context, a fourth, potentially fast-acting, low-cost, and high-leverage way to limit increasing global temperatures and their attendant effects offers a tempting bridging option. That method is sunlight reflection n, which entails reflecting a small percentage of sunlight back into space to counteract its warming effect on greenhouse gases (GHGs).
The potential value of sunlight reflection—also known as solar geoengineering and solar climate intervention (SCI)—is high.
The idea of reflecting sunlight to reduce heat in the earth system has existed since the 1960s, but it did not attract serious consideration until 2006, when Nobel Prize laureate Paul Crutzen published an influential article on the topic. The leading methods proposed to enhance Earth’s reflectiveness are the stratospheric dispersal of aerosols (solid or liquid particles suspended in air) and the brightening of low-lying marine clouds. Often relegated to science fiction, such intervention has gained plausibility thanks to advances in atmospheric research and computer modelling. Scientific observations and models suggest that it offers a technologically plausible, potentially rapid, and relatively inexpensive way to slow or even reverse the rise in global temperatures caused by climate change, possibly reducing the hazards associated with dramatic warming while nations and international bodies make steady progress on the massive, protracted tasks of decarbonizing the world economy and stabilizing (and ultimately reducing) atmospheric GHG concentrations. It thus deserves genuine consideration by policymakers as another arrow in the quiver of climate risk–management strategies, alongside and supplementary to emissions cuts, CDR, and adaptation. Indeed, given the stakes, it would be irresponsible for national leaders not to evaluate the viability and possible consequences of SCI.
Recognizing the promise of sunlight reflection, the Intergovernmental Panel on Climate Change (IPCC) mentioned SCI in its 2018 special report as one method with a very high chance of keeping the increase in global temperatures below 1.5°C. It thus warrants thorough study as a potential complementary approach to the climate risk–management strategies currently being applied.
Nevertheless, critics have raised several practical objections to and ethical qualms about the prospect of sunlight reflection. While these concerns merit scrutiny and assessment, danger is always relative. Potential risks need to be evaluated and weighed not in isolation but in the context of the known hazards that humanity is already courting by continuing to pump vast quantities of GHGs into the atmosphere.
The question is how the anticipated threats to human safety and well-being posed by climate change compare with those presented by climate change plus sunlight reflection. In other words, would the world be worse or better off were it to add sunlight reflection to its mix of climate responses?
Unfortunately, the world is not yet in a position to answer that question, given critical basic knowledge gaps about the potential efficacy and repercussions of such interventions and a paucity of norms or rules governing the intentional manipulation of Earth’s climate system. Indeed, governments have been reluctant even to discuss the issue openly.
This situation is untenable; to confront a future of dramatic warming, humanity needs to consider all its options. Concomitantly, sunlight reflection involves techniques that carry risks of unintended consequences—dangers that could be magnified by uncoordinated and independent development and use.
Governments thus need a vastly improved scientific understanding of the feasibility and effects of sunlight reflection to make informed and responsible choices regarding its application. They also need an anticipatory international framework to govern any deployment decision, so that they do not find themselves scrambling and divided without agreed rules and procedures in some future moment of crisis.
The writer is a student at QAU, Islamabad.
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