Emily's Global Climate Change Scrapbook

Proxy indicators are aspects of the environment which scientists can use in place of direct measurements to gain understanding about past climate conditions.

-By extracting ice cores scientists can determine much about past climate.

-As ice and snow have accumulated over the years, tiny pockets of air were trapped between layers.

-This air can be tested to determine the composition of the atmosphere, the levels of greenhouse gases, amounts of precipitation, and general temperature.

- Scientists studying past climate can also obtain cores of ocean sediment.

- Often times remnants of pollen are trapped between layers of sediment.

- From pollen, scientists can determine the types of plants that once grew there and, as certain plants only grow in certain climates, this can provide a good picture of past climate.

- Much can be determined about past climate from coral reefs, as many have been around for thousands of years and they are quite sensitive to changes in climate.

- Scientists can make deductions about past temperature based on their calcium carbonate skeletons, which form growth rings similar to trees.

- From these creatures we can determine the isotopic ratio of oxygen, which can reveal sea surface temperatures.

- Age isn't the only thing you can tell about a tree from its rings. They also provide clues about how the climate was decades or even centuries ago.

- The temperature and amount of precipitation is shown through the width of the rings. The wider the ring is, the more the tree grew. Years with wider rings generally were warmer and had greater amounts of precipitation.

- Charred tree rings also signify years where forest fires took place, indicating a hotter dryer year.