Role of net zero emissions to mitigate global warming

Dr. Mukul Chandra Bora

(Director, Dibrugarh University Institute of Engineering and Technology Dibrugarh University)

Since 1880, the average global temperature has experienced an increase of approximately 1 degree Celsius (equivalent to 1.7 degrees Fahrenheit). Projections indicate that global temperatures are expected to rise by approximately 1.5 degrees Celsius (equivalent to 2.7 degrees Fahrenheit) by 2050 and between 2 and 4 degrees Celsius (equivalent to 3.6 and 7.2 degrees Fahrenheit) by the year 2100. Scientists have constructed a comprehensive record of Earth’s climate by examining various indirect indicators, including ice cores, tree rings, glacier lengths, pollen remnants, and ocean sediments. Additionally, they have studied changes in the Earth’s orbital patterns around the sun. This extensive record reveals that the climate naturally fluctuates across various time scales. However, this natural variability cannot account for the observed warming since the 1950s. Instead, it is highly probable (>95%) that human activities have primarily driven this warming. Human actions have significantly contributed to climate change through two key factors: greenhouse gas emissions and alterations in the Earth’s surface’s ability to reflect or absorb solar energy.

Greenhouse Gases: Concentrations of crucial greenhouse gases have surged since the Industrial Revolution due to human activities. Carbon dioxide, methane, and nitrous oxide levels now exceed those seen in the Earth’s atmosphere for the past 800,000 years. These emissions have intensified the greenhouse effect, resulting in an increase in the Earth’s surface temperature. Among human activities, the burning of fossil fuels stands out as the most influential contributor to climate change.

 Carbon Dioxide: Human activities currently release more than 30 billion tonnes of carbon dioxide into the atmosphere annually. Atmospheric carbon dioxide concentrations have risen by over 40 percent since the pre-industrial era, from approximately 280 parts per million (ppm) in the 18th century to 414 ppm in 2020.

 Methane: Human activities raised methane concentrations to over 2.5 times the pre-industrial levels during most of the 20th century, from around 722 parts per billion (ppb) in the 18th century to 1,867 ppb in 2019.

 Nitrous Oxide: Nitrous oxide concentrations have increased by roughly 20 percent since the onset of the Industrial Revolution, with a notable acceleration towards the end of the 20th century. Nitrous oxide concentrations have risen from a pre-industrial level of 270 ppb to 332 ppb in 2019.

Reflectivity or Absorption of Solar Energy: Human activities, such as agriculture, road construction, and deforestation, can alter the reflectivity (albedo) of the Earth’s surface, leading to localised warming or cooling effects. This phenomenon is evident in urban heat islands, where urban areas tend to be warmer than less populated surroundings due to buildings, pavement, and roofs reflecting less sunlight compared to natural surfaces. Although deforestation can increase the Earth’s overall reflectivity by replacing dark forests with lighter surfaces like crops, the net impact of all land-use changes appears to result in a modest cooling effect.

Furthermore, emissions of small particles known as aerosols into the atmosphere can also affect the reflection or absorption of solar energy. Many types of air pollutants undergo chemical reactions in the atmosphere, producing aerosols. Overall, human-generated aerosols tend to have a net cooling effect on the Earth’s climate.

Natural Phenomena Natural phenomena have perpetually influenced the Earth’s climate, offering explanations for climate fluctuations dating back to periods preceding the Industrial Revolution in the 1700s. Nevertheless, contemporary climate alterations cannot be solely attributed to natural factors.

Alterations in Earth’s Orbital Dynamics and Rotation Modifications in the Earth’s orbit and axial rotation have wielded significant influence over climate throughout history. For instance, alterations in the planet’s orbit have notably impacted the quantity of summertime sunlight in the Northern Hemisphere, which is linked to the primary driver of past ice age cycles. These cycles encompass prolonged intervals of frigid temperatures (ice ages) and shorter interglacial epochs (intermediate warm periods) with relatively higher temperatures. During the peak of the last glacial period, global temperatures averaged approximately 11°F colder than the present era. Conversely, during the zenith of the last interglacial period, global temperatures were at most 2°F warmer than today.

Fluctuations in Solar Activity Variations in the sun’s energy output can influence the intensity of sunlight reaching the Earth’s surface. While these fluctuations can impact the Earth’s climate, recent decades have witnessed solar variations playing a negligible role in observed climate changes. Satellite measurements of solar energy reaching Earth since 1978 reveal no net increase in solar output, even as global surface temperatures have surged.

Changes in Earth’s Albedo: The extent to which the Earth absorbs or reflects sunlight is contingent on its surface and atmosphere. Dark surfaces and objects, such as oceans, forests, and soil, tend to absorb more sunlight, whereas light-coloured surfaces like snow and clouds reflect sunlight. Approximately 70 percent of incoming sunlight is absorbed by the Earth. Natural alterations in the Earth’s surface, such as sea ice melting, have historically contributed to climate fluctuations, often functioning as feedback mechanisms within the broader climate system.

Volcanic Activity Volcanoes have left an indelible mark on Earth’s climate, with volcanic eruptions releasing substantial quantities of carbon dioxide in the distant past. Certain explosive volcanic eruptions can propel particles, such as sulphur dioxide (SO2), into the upper atmosphere. These particles can reflect sufficient sunlight back into space, resulting in surface cooling lasting several years. These particles exemplify cooling aerosols.

Nevertheless, volcanic particles from a single eruption do not exert a long-term influence on climate as they remain in the atmosphere for significantly shorter durations than greenhouse gases. Furthermore, human activities emit more than 100 times the amount of carbon dioxide compared to volcanic emissions each year.

Shifts in Naturally Occurring Carbon Dioxide Levels Over the past few hundred thousand years, carbon dioxide levels have synchronised with glacial cycles. During warm interglacial periods, carbon dioxide concentrations were elevated, whereas cool glacial epochs saw reduced carbon dioxide levels. Alterations in the Earth’s surface and ocean temperatures can provoke changes in the sources and sinks of these gases, thereby affecting greenhouse gas concentrations in the atmosphere. These fluctuating concentrations have served as a positive climate feedback mechanism, amplifying temperature variations stemming from long-term shifts in Earth’s orbital dynamics.

As a result of the global increase in air temperatures, the entire planet is facing a looming crisis where it may become uninhabitable for both humans and other species. Without immediate action to reduce greenhouse gas emissions and carbon dioxide levels in the atmosphere, our world is at risk of disappearing. Moreover, the rising global temperatures are causing the polar ice caps to melt, leading to a rise in sea levels. This, in turn, poses a severe threat to the inhabitants of small island nations, numbering around 600. According to a United Nations study, by 2100, five nations—the Maldives, Tuvalu, the Marshall Islands, Nauru, and Kiribati—may no longer be habitable, resulting in 600,000 stateless climate refugees.

President Mohamed Nasheed of the Republic of the Maldives has warned that if sea levels rise by over 1.5 metres, hundreds of millions of lives could be lost and entire communities could be wiped out. It’s crucial to recognise that Small Island Developing States (SIDS) are already grappling with escalating challenges like rising tides, cyclones, floods, crop damage, increased diseases, coastal area inundation, and freshwater shortages. These nations are on the front lines of climate change, even though they have contributed the least to global warming. The era of mass fossil fuel consumption in the post-industrial age has significantly accelerated carbon dioxide (CO2) levels to dangerous degrees, causing harm to the environment and infrastructure in many SIDS and low-lying regions.

The less affluent countries situated near large bodies of water, which have had minimal contributions to global warming and sea-level rise, now find themselves at the mercy of historical polluters. Developed nations in the global North are rapidly losing credibility in this regard. Ambassador Ronny Jumeau, Permanent Representative of the Seychelles to the United Nations, aptly described this situation: “Let’s say my neighbour flooded my house entirely on his own, while I didn’t contribute. Yet, I have to now borrow money from him, then pay him interest for the rest of my life, in order to clean up the mess in my house that he is responsible for. This is dishonest.”

Throughout the 20th century, the global sea level rose by approximately 7.5 inches. The United Nations warns that it could rise an additional three feet by the end of the 21st century, potentially wiping out eight small island nations. Those responsible for the global temperature rise will bear the responsibility for the loss of lives in these countries. Rising sea levels and shifting climate patterns, including more frequent and severe storms, are compounding the challenges faced by these vulnerable nations, pushing them further underwater. Global warming, primarily driven by the actions of the most polluting countries, is responsible for these rising sea levels and changing climate patterns.

Net Zero Solution: The concept of “net zero” signifies a state in which the amount of greenhouse gases (GHGs) produced is balanced by the amount removed from the atmosphere. Achieving net zero emissions is crucial for ensuring a sustainable future and mitigating the effects of climate change. This can be accomplished through a combination of reducing emissions and implementing strategies for carbon removal. Net zero, also referred to as “carbon neutrality” or “climate neutrality,” involves reducing greenhouse gas emissions responsible for global warming to zero by offsetting them with removal and storage through carbon sinks.

To attain the net zero target for a sustainable energy transition, it is essential to revolutionise the way energy is generated, consumed, and managed. This transition aims to balance the greenhouse gas emissions associated with energy use by generating renewable energy and reducing emissions in various sectors. Here’s a brief overview of the energy sources and strategies needed for achieving net zero emissions:

1. Renewable Energy: Renewable energy sources such as solar, wind, hydro, and geothermal power play a crucial role in achieving net zero emissions. These sources are abundant, environmentally friendly, and have minimal to zero carbon emissions, making them essential for reducing our reliance on fossil fuels.

2. Green Hydrogen Energy: Hydrogen has the potential to contribute significantly to achieving net zero emissions. However, it is crucial to produce hydrogen using sustainable methods, as current practices often involve fossil fuels and result in substantial carbon dioxide emissions.

3. Nuclear Energy: Nuclear power is a carbon-free energy source that can complement renewable energy. It has the potential to provide clean energy for various sectors, including transportation and buildings.

4. Wind Energy: Wind electricity generation has seen significant growth, and it is a key component of achieving net zero emissions. Expanding wind energy capacity and increasing generation rates are essential for meeting emission reduction goals.

5. Tidal Wave Energy: Tidal power, generated from oceanic and tidal waves, offers a renewable energy source with minimal carbon emissions. While it is not as developed as other renewables like wind and solar, it holds promise for the future.

From the discussion above, it becomes evident that human activities, particularly one-sided developmental approaches, are responsible for the current state of global warming and climate change. It is imperative that people around the world take collective action to mitigate this crisis and ensure a habitable Earth. Our energy sources must be environmentally friendly, produce zero carbon emissions, and support the goal of net zero emissions, or else our beautiful planet and its diverse ecosystems will be at risk.