These are the 5 reasons why scientists think we are in a climate emergency

Earthlings are in a race against time to save the planet from some of the worst consequences of the ongoing climate emergency.

Representational image | Pixabay

New Delhi: The Oxford Dictionaries last month announced ‘climate emergency’ as the ‘Word of the Year’ for 2019. 

The title is given to “a word or expression shown through usage evidence to reflect the ethos, mood, or preoccupations of the passing year, and have lasting potential as a term of cultural significance”.

The use of the term, the Oxford Dictionaries said, increased 100-fold between 2018 and 2019, soaring from “relative obscurity” to “one of the most prominent — and prominently debated — terms” of the year. 

The global groups Fridays for Future and Extinction Rebellion have changed the narrative around climate change, raising it from a passive background discussion to the status of emergency.

The use of such alarming language is not just a PR strategy to engage the public. The emergency of climate change is very real and rooted in five major reasons, according to scientists and experts.

1. CO2 concentration

The World Meteorological Organisation (WMO) Greenhouse Gas (GHG) Bulletin, released on 25 November, said “globally averaged concentrations of carbon dioxide (CO2) reached 407.8 parts per million in 2018, up from 405.5 parts per million (ppm) in 2017”. 

This is the highest level in at least the past 3 million years. 

The last time CO2 concentration was this high, the report noted, temperatures were 2-3°C higher and sea levels 10-20 m higher than today.

Other greenhouse gases such as methane and nitrous oxide and water vapour are also on the rise. With no signs of peaking, global emissions of GHGs continue to rise at a pace that is unprecedented in the history of the planet.

2. Climate projections may be too conservative

Global climate models (GCMs), which comprise mathematical equations to describe the physical processes in the atmosphere, oceans and on land, are used to project how climatic conditions will change in the future under different greenhouse gas concentrations. 

The wide-ranging scales of environmental processes and the inter-connectedness of the climate system make modelling extremely challenging. 

All climate models, therefore, use simplified descriptions and make certain approximations to make calculations feasible. Such simplifications inevitably introduce uncertainties in projections. In fact, recent observational trends suggest that model projections tend to be too conservative. 

The UN Intergovernmental Panel on Climate Change (IPCC) projected in their 2018 special report that global sea level will rise anywhere between 0.26 and 0.77 m at 1.5°C of global warming. 

Observational trends, however, suggest that sea level rise is currently on track to be as high as 0.8 m from the melting of Greenland and Antarctic ice sheets alone. 

One of the reasons for the discrepancy with projections is that models fail to take into account the accelerating rate of ice-sheet melt due to various physical phenomena such as meltwater lakes on the surface of ice sheets or warm water encroachment from the ocean underneath.

3. At the mercy of tipping points

One of the major reasons why climate models fail to capture the potential speed of climate change is ‘tipping points’. There are many so-called ‘tipping points’ all across the atmospheric, oceanic and cryogenic spheres of our climate, where small gradual changes in one component can lead to large irreversible changes in the entire system.

Scientists believe we may have already crossed some of them. For instance, the Arctic Sea ice tipping point. Small initial warming in the Arctic started melting the sea ice — as sea ice melts, the white surface is replaced by dark blue ocean water, which absorbs more heat and melts even more ice.

Because of this self-reinforcing cycle, the Arctic region will continue to warm irreversibly at accelerating rates to a state where there is no sea ice in the summer months. Water absorbs a lot more heat than ice, which is why having blue ocean water for months in the Arctic would further increase temperatures.

The reason why this is particularly worrisome is because crossing one tipping point can trigger others, leading to a cascade. For example, the abrupt warming due to loss of Arctic sea ice could trigger abrupt, irreversible melting of the neighbouring Greenland ice sheet, which would, in turn, be a tipping point for global sea level rise.

4. Species extinction

The most striking symptom of the climate emergency underway is, perhaps, the rate at which species around the world are going extinct. 

A recent report by the UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), which analysed over 15,000 scientific and government studies from the past five decades, noted that the health of ecosystems on which all species, including human beings, depend is deteriorating faster than ever.

Primarily driven by a combination of factors that result from climate change and reckless human exploitation, around 10 lakh animal and plant species currently face the threat of extinction, many within decades. This is more than ever before in human history. 

Scientists believe that we may be in the middle of the Sixth Mass Extinction. Mass extinctions on our planet have primarily been caused by abrupt climatic changes, and are marked by several species going extinct in a short period.

5. Lack of leadership

While the signs of climate change have never been more obvious, political leadership at the highest levels is looking the other way. US President Donald Trump has publicly denounced the science behind climate change and peddled conspiracy theories.

In the summer of 2017, Trump announced that the US will leave the Paris Agreement, signed by 196 countries in 2015 as a last-ditch global effort to mitigate warming, with the decision scheduled to officially take effect on 4 November 2020.

Brazil’s far-right government, under the leadership of President Jair Bolsonaro, has vowed to end or loosen protections for the Amazon rainforest in favour of the powerful agri-business industry.

In India, climate change and environmental issues rarely make it to political debates and elections. 

Local and national governments continue to shrug off responsibility and ignore the growing pollution and ecological crisis as lakhs of citizens suffer the consequences in the backdrop.

Recent years, however, give reason for hope. Following pressure from protests and demonstrations, some governments at the local and national levels have heeded the advice of young activists and declared a climate emergency. Most notably, last month, the European Parliament, comprising 28 member states, declared a climate emergency.

Whether this movement will be the turning point is a question that will be answered when — and if — governments around the world not only declare a climate emergency but also take the steps required to halt abrupt climate change.

(Edited by Sunanda Ranjan)

The author is a freelancer and has a keen interest in the science of climate change and the environment.