What are the Effects of Global Warming on Plants?

Global warming refers to the general increase in the atmospheric temperature across the Earth due to greenhouse gases emitted due to various human activities. It happens primarily due to the excess CO₂ generated along with other harmful gases from industries. The effects of global warming on plants are widely visible across the globe. This has led to the overall increase in average temperature, which is causing a domino effect on other areas as well.

Major Effects of Global Warming on Plants and the Environment

The major effects of global warming on plants are summarised below.

1. Increased Productivity

As the amount of CO₂ in the atmosphere increases, plants increase their photosynthetic rate, and that reflects in an overall increase in productivity. This effect is called the carbon fertilisation effect.

This increase in photosynthesis accelerates the plant growth in some species, especially those of wheat, soybeans, rice, etc.
As the photosynthesis increases, plants can keep their stomata partially closed to reduce the water loss by about 5-20%.
This helps them retain water in the soil and release less into the atmosphere.

2. Nitrogen Availability Reduced

While an increase in photosynthesis is an advantageous effect of global warming in plants, it shows some negative effects as well. It is evident in the case of nitrogen deficiency.

It happens when the plant takes in more CO₂and creates carbohydrates; this increase in CO₂ concentration in the leaves reduces the concentration of nitrogen.

The reduced amount of nitrogen negatively affects plant productivity. The plant fails to capitalize on the increased productivity by photosynthesis, as it will be unable to sustain it for a long time.

Increased temperature in the atmosphere reduces the response of nitrogen-fixing bacteria, leading to a reduction in the nitrogen availability in the soil.

3. Effects on Enzymes

An increase in atmospheric temperature negatively affects the nitrogen-containing enzymes. In the case of Rubisco, the enzyme crucial for carbon fixing, increased temperature makes the enzyme less efficient, and it will be unable to hold the CO₂ molecule.

In some cases, the Rubisco enzyme ends up fixing an oxygen molecule, instead of CO₂. In worst cases, higher temperature makes this enzyme completely inactive or deactivates it.

As plants often respond with an increased production of Rubisco when supplied with nitrogen fertilizers, it can be used to overcome the decreased efficiency of this enzyme under higher temperature conditions.

4. Pest, Pathogens, and Diseases

Global warming causes a warmer winter than usual, which will create an ideal scenario for the pests and pathogens to grow. As the growing seasons get longer due to this temperature variation, more pest generations grow, which can damage the crops.

Higher moisture content with the temperature rise makes the crops more vulnerable to pathogenic attacks. It also makes way for more weed growth. All these affect the crop growth and cause loss.

5. Reduced Yield

The increase in photosynthesis makes the plant grow faster, and its life cycle is shortened. As a result, there will be reduced size, number, or quality of the crops, making the overall yield smaller.

The ongoing adaptations of the plant to the changing climate also affect the yield. At the same time, some plants can increase their yield with the changing environment.

Effects of Global Warming on the Environment

1. Glacier Melting

One of the biggest impacts of global warming is seen in the large-scale melting of the polar glaciers. The drop in the Arctic Sea ice is estimated to be 10% per decade. This has been measured since the satellite monitoring in 1978. There is also a considerable decrease in the winter rainfall as well as the snowpack in many regions.

2. Sea Level Rise or Rising Sea Level

The past two centuries have observed an increase in sea level of 0.17 to 0.21m. The mass loss in glaciers and an increase in thermal expansion in the ocean have cumulatively increased the sea level. It is predicted to increase at a rate of 3.21mm per year.

3. Flooding

Flooding of the low-lying areas near the coast is another consequence. The rise in sea level causes coastal flooding, forcing people to find alternatives. At the same time, several islands would also disappear.

4. Acidification of Oceans

Ocean water is generally alkaline with a pH range of 8 to 8.3. Due to the increase in CO₂ in the atmosphere, it can reduce the alkalinity of seawater and make it acidic. CO₂ is soluble in seawater, which will generate carbonic acid. The increase in carbonic acid causes acidification of the ocean.

The burning of fossil fuels is the biggest culprit for this phenomenon. The ocean is estimated to absorb around ¼ or ⅓ of the CO₂ thus generated. This changes the water pH, which will cause adverse effects in the aquatic ecosystem.

5. Impact on Ecosystems

The increase in global temperature forces species to adapt to the changing conditions. Those who fail will become extinct sooner. This rate of extinction will be greater than the natural process. With the temperature rise, there will be climate changes that will also affect individuals and ecosystems. The shift in habitat for several species towards the poles is also seen as they prefer higher altitudes.

Early migration of animals and birds is commonly seen. Plants have also changed their blooming season. An increase in diseases and epidemics is another impact of global warming on plants.

6. Precipitation Changes

In the past few decades, a change in precipitation pattern and frequency has been observed. There is a larger increase in precipitation, which is not distributed uniformly or as it used to be. An increase in quantity and duration of precipitation has led to floods and heavy rainfall even in unexpected areas or regions.

7. Extreme Weather Patterns

Global warming will have long-term effects on the global weather conditions. Hot weather will soon be the prevalent weather with extreme summer, heavy rainfall, and an increase in dry or drought conditions. Heat waves during summer may very well be a common occurrence. There will be a reduction in cold weather either in average temperature or its duration. But extreme cold conditions may also be observed.

References

Shukla, R.S. and Chandel, P.S. (2001) Plant Ecology. S. Chand and Company Ltd., New Delhi.
Verma, P.S., Agarwal, V.K. (1999). Cell Biology, Genetics, Molecular Biology, Evolution, and Ecology. New Delhi: S.Chand Co.(Pvt) Ltd.
https://news.climate.columbia.edu/2022/01/27/how-climate-change-will-affect-plants/