Global challenges Study Guide

The distribution of organisms, meaning where they live and in what numbers, is significantly affected by various environmental factors. Changes to these factors, such as the availability of water, levels of atmospheric gases, temperature, and light intensity, can lead to shifts in species distribution. For example, a decrease in water availability can force drought-sensitive species to migrate or decline in population, while drought-resistant species might expand their range. Similarly, changes in atmospheric gas concentrations, particularly carbon dioxide and pollutants, can have profound effects. Increased carbon dioxide levels contribute to global warming, altering habitats and affecting temperature-sensitive species. Acid rain, caused by sulfur dioxide and nitrogen oxides reacting with atmospheric water, can acidify soil and water bodies, negatively impacting plant growth and aquatic life. Scientists collect and evaluate evidence from long-term monitoring studies, fossil records, and experiments to understand these complex relationships. This evidence allows us to identify trends, predict future impacts, and inform conservation strategies. Evaluating the reliability and validity of this evidence is crucial for making accurate assessments of environmental change effects.

Non-communicable diseases (NCDs) are conditions that are not caused by infectious agents and cannot be spread from person to person. Examples include heart disease, cancer, mental illnesses, and diabetes. Unlike communicable diseases, NCDs typically develop over a long period due to a complex interplay of various factors. It's rarely just one cause; instead, it's often a combination of genetic predispositions, lifestyle choices, and environmental influences. For instance, heart disease can be influenced by inherited genes (genetics), smoking, poor diet, and lack of exercise (lifestyle), as well as exposure to certain air pollutants (environmental). Similarly, type 2 diabetes has strong genetic links but is heavily promoted by dietary habits and physical inactivity. Certain cancers are linked to specific gene mutations, but also to environmental carcinogens like UV radiation or chemicals in tobacco smoke. Mental health conditions also have both genetic components and are significantly impacted by social and psychological environmental factors. Understanding this multi-factorial nature is crucial for prevention, diagnosis, and treatment strategies, as addressing only one factor may not be sufficient to mitigate the disease risk or progression.