Geography · Ch 17 — World Climate and Climate Change
Global Warming
Global Warming
The diagram is a collage of real newspaper clippings and photographs, arranged to show how global warming is reported in the media. It is not a single scientific figure but a collection of news stories, each with its own headline, image, and caption. The overall message is that global warming is not an abstract idea — it is happening in specific places, with measurable effects that journalists are documenting.
The top-left clipping carries the headline "Greenhouse gases rising alarmingly" and refers to "Ancient Air Bubbles Buried In Antarctic Ice To Shed More Light On Global Warming." Beside it are two photographs: one of an iceberg and one of an Antarctic ice-coring research station. This story connects the greenhouse effect to polar science — scientists drill into ancient ice to extract trapped air bubbles, which reveal past atmospheric composition and help confirm that greenhouse gases have increased. The iceberg photo reminds us that warming affects polar ice directly.
Another clipping is headlined "ICE AGE cometh," reporting on a possible cooling of the North Atlantic. This seems contradictory at first, but it illustrates a real consequence of climate change: melting freshwater from ice sheets can disrupt ocean currents, potentially cooling certain regions even as the planet warms overall. The diagram thus shows that global warming does not mean uniform warming everywhere — it can trigger complex, sometimes counterintuitive regional changes.
A photograph shows dead fish on a dried reservoir bed in China's Hainan island. This is a direct, visible impact of drought — a warmer climate can intensify evaporation and alter rainfall patterns, leading to water shortages that devastate ecosystems and livelihoods. The image is stark because it shows a concrete, local tragedy caused by a global phenomenon.
A headline reads "Gangotri is shrinking 23m every year," accompanied by a satellite image showing the Gangotri glacier's terminus retreat since 1780. This is a Himalayan example of glacial retreat — the glacier's front edge is moving backward each year, and the satellite imagery provides long-term visual evidence of the change. The Gangotri glacier is a major source of the Ganga, so its retreat has serious implications for water supply in northern India.
A final headline mentions "Warming Arctic could affect world weather," linking polar warming to global atmospheric circulation. The Arctic is warming faster than most regions, and this can alter jet streams and weather patterns far beyond the poles. …
The atmosphere, because of certain gases, behaves like a greenhouse. It lets sunlight in but traps much of the heat the Earth sends back out. This is the core of global warming, and it starts with understanding how energy moves through the atmosphere.
Incoming solar radiation is short-wave, and the atmosphere lets most of it pass through to warm the Earth's surface. But the Earth, once heated, radiates energy back upwards as long-wave radiation. The atmosphere does not let most of this long-wave radiation escape. Instead, it absorbs it. The gases responsible for this absorption are called greenhouse gases. The collective warming of the atmosphere that results from this process is called the greenhouse effect.
The name comes from an analogy. A greenhouse used in cold regions is built of glass. Glass is transparent to incoming short-wave solar radiation, so sunlight enters easily. But glass is opaque to outgoing long-wave radiation, so the heat inside cannot escape. More radiation enters than leaves, and the temperature inside the glasshouse rises above the temperature outside. The atmosphere behaves the same way: it transmits short-wave radiation from the sun but absorbs most of the long-wave radiation from the Earth. …
Due to the presence of greenhouse gases, the atmosphere is behaving like a greenhouse. The atmosphere also transmits the incoming solar radiation but absorbs the vast majority of long wave radiation emitted upwards by the earth's surface. The gases that absorb long wave radiation are called greenhouse gases. The processes that warm the atmosphere are often collectively referred to as the greenhouse effect.
The annual average near-surface air temperature of the world is approximately 14 degree C. An increasing trend in temperature was discernible in the 20th century. The greatest warming of the 20th century was during the two periods, 1901-44 and 1977-99. Over each of these two periods, global temperatures rose by about 0.4 degree C. In between, there was a slight cooling, which was more marked in the Northern Hemisphere. …