Question

The overall increase in the air temperature in the 20th century has been about

• A. 1.0 - 1.5 Ā°C
• B. 0.2 - 0.8 Ā°C
• C. 0.9 - 1.2 Ā°C
• D. 1.5 - 2.0 Ā°C

Hint:

Global Warming Benchmarks: 20th Century Temperature Rise = $0.2 - 0.8^\circ\text{C}$ (Average $\approx 0.6^\circ\text{C}$).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Global historical climatology: IPCC Third Assessment Report (TAR) established that global mean surface air temperature increased by $0.6 \pm 0.2^\circ ext{C}$ ($0.2^\circ - 0.8^\circ ext{C}$) over the 20th century.
Key Formula or Approach:
\[ \Delta T_{\text{20th Century (IPCC)}} \approx 0.6^\circ\text{C} \pm 0.2^\circ\text{C} \quad (0.2^\circ\text{C to } 0.8^\circ\text{C}) \]

Step 2: Detailed Explanation:
In climatology and global warming assessment (IPCC historical records):
- Over the course of the 20th century (1901 to 2000), instrumental meteorological records show that the global average surface air temperature increased by approximately $0.6^\circ ext{C$ (with a documented scientific range of 0.2 to 0.8 Ā°C $0.6 \pm 0.2^\circ ext{C}$)}.
- This historical baseline is standardly referenced in agricultural ecology and animal biometeorology curricula.

Step 3: Final Answer:
Thus, the overall increase in the 20th century was about 0.2 - 0.8 Ā°C, corresponding to option (B).