GREENWICH, CT.- Hot deserts, soggy rainforests, arctic tundra and temperate forests – these are a few climatic regions spread across our planet. Unlike weather, which is chaotic and difficult to predict on a daily basis, climate is the expected weather for an area averaged over time. But climate is not static and itself changes with time. The new exhibition Climate Change: From Snowball Earth to Global Warming explores our planet’s history of climate shifts, explains some of the causes, and highlights the challenges and responses to current global warming.

While records from weather instruments provide good data for the last 100 years of climate on Earth, scientists use a variety of methods to reconstruct climate from earlier ages. About 700 million years ago, the entire Earth was so cold that scientists refer to it as “snowball Earth,” where few organisms other than hardy single-celled bacteria survived. Fossil evidence of these and the first multi-celled life forms that developed as the planet warmed are on view in the exhibition. Fossil plants and animals such as a 110-million-year-old subtropical fern from Washington state and the skull of a crocodile that roamed Utah 45-million years ago, represent a time when the Earth was significantly warmer than it is today. A section of a bristlecone pine tree from California documents growing conditions from 2219 BC to AD 1956 and a part of a South Pacific coral core drilled in 2004 dates to 1836.

Currently, Earth’s climate is warming and scientists continue to need good data with global coverage. The APEX profiler is one of over 3,000 floating devices that send temperature data from the world’s oceans to international climate data centers. The current warming is affecting entire ecosystems – from the arctic to the tropics. On display are examples that underscore the impacts: the polar bear that requires extensive sea ice for successful hunting is now a threatened species; corals, cod and a sea urchin represent marine organisms that are having difficulty adapting to the changing conditions in the oceans; the extinction of the golden toad of Costa Rica and early egg laying of tree swallows have both been attributed to global warming.

Changing climates affect human culture, too. An Anasazi pot in the exhibition reminds the visitor of an ancient culture of the US Southwest that thrived in a relatively wetter period, but then disappeared, likely in part as the result of drought and unstable climatic conditions. Today, agricultural scientists are developing different strains of rice that can withstand an uncertain future of salty water, drought or excess water.

The exhibition also describes some of the causes of variation in Earth’s climate. Interactive stations invite visitors to understand the complex, dynamic processes of the climate system and express their understanding of and response to current global warming.