Climate change is one of the most significant environmental challenges facing the world in the modern era, as it directly and indirectly affects ecosystems and the living organisms inhabiting them. Climate change refers to long-term changes in temperature, rainfall patterns, wind patterns, and weather events resulting from natural and human factors, particularly increased greenhouse gas emissions caused by fossil fuel combustion, deforestation, and industrial activities. Biodiversity is fundamental to the continuation of life on Earth because it encompasses the diversity of plants, animals, microorganisms, and different ecosystems. Therefore, understanding the relationship between climate change and biodiversity is an important step toward protecting the environment and ensuring the sustainable use of natural resources. First: The Concept and Causes of Climate Change Climate change refers to long-term shifts in climatic conditions, such as rising global average temperatures, changes in precipitation rates, more frequent heatwaves, droughts and floods, and rising sea levels. The main causes of climate change include fossil fuel combustion, which increases carbon dioxide emissions through the use of coal, oil, and natural gas in industry, transportation, and energy production. Deforestation also contributes to climate change by reducing the capacity of vegetation to absorb carbon dioxide, while simultaneously causing the loss of habitats for numerous living organisms. Industrial and agricultural activities release greenhouse gases, such as methane and nitrous oxide, which contribute to global warming. Urban expansion also destroys and fragments natural habitats, placing additional pressure on plant and animal species. Second: The Concept and Importance of Biodiversity Biodiversity refers to the variety of life on Earth, including living organisms, their genetic variation, and the ecosystems in which they exist. It can be divided into three main levels: genetic diversity, which represents genetic differences among individuals of the same species; species diversity, which refers to the variety of plant, animal, and microbial species in a particular area; and ecosystem diversity, which encompasses different environments such as forests, deserts, wetlands, seas, and oceans. Biodiversity is essential for maintaining ecological balance, providing food, medicine, and raw materials, supporting agriculture and natural pollination, purifying water and air, and regulating the climate. It also enhances the ability of ecosystems to withstand disturbances and recover from them. Third: The Effects of Climate Change on Biodiversity Climate change affects biodiversity in several ways, most notably through rising temperatures. Higher temperatures alter the environmental conditions required by living organisms for survival and reproduction. Some species may be forced to migrate toward cooler regions or higher elevations, while others may be unable to adapt to rapid changes, increasing their risk of extinction. Climate change also contributes to habitat loss and degradation. Many natural habitats are affected by drought, wildfires, and rising sea levels. Melting ice reduces the habitats available to certain polar animals, while wetlands and forests may undergo significant changes or disappear altogether. Marine life is also vulnerable to climate change. The absorption of carbon dioxide by the oceans increases seawater acidity, harming organisms that depend on calcium carbonate to build their shells and skeletons. Rising water temperatures can also cause coral bleaching, threatening the many organisms that rely on coral reefs for food and shelter. Changes in temperature and rainfall patterns can disrupt breeding and migration seasons. For example, some plants may flower earlier than usual, while their flowering periods may no longer coincide with the activity of pollinating insects. This mismatch can affect plant reproduction and agricultural production. Furthermore, climate change increases the risk of species extinction, particularly among species with restricted geographical ranges or limited capacity to adapt. When species disappear from their habitats, food-web relationships and ecological balances may be disrupted, triggering further effects on other organisms. Changes in temperature and humidity may also expand the distribution of certain insects, pests, and disease-causing organisms. This can affect wild plants, agricultural crops, and animals, in addition to increasing certain health risks for humans. Fourth: The Impact of Climate Change on Biodiversity in Iraq Iraq is among the countries facing environmental challenges associated with rising temperatures, water scarcity, and recurring droughts. These conditions affect biodiversity across desert, agricultural, wetland, and river ecosystems. Rising temperatures and prolonged droughts place additional pressure on natural vegetation and wildlife, while declining water availability threatens aquatic organisms and the habitats that depend on rivers and wetlands. The Iraqi marshlands, in particular, are vulnerable to reduced water supplies and changes in water quality, which can affect fish, birds, plants, and other organisms that depend on these habitats. Agricultural ecosystems may also experience changes in species distribution and increased pressure from pests, while desertification and habitat degradation can threaten native plant and animal populations. Protecting biodiversity in Iraq requires sustainable water management, the conservation and restoration of wetlands and other natural habitats, the protection of native species, and the expansion of environmental monitoring and scientific research. Reducing greenhouse gas emissions and adopting climate-adaptation measures are also important for strengthening ecosystem resilience and safeguarding the country's natural resources. In conclusion, climate change poses a major threat to biodiversity by altering habitats, disrupting biological processes, and increasing the risk of species decline and extinction. In Iraq, these effects are particularly important because of water scarcity, rising temperatures, and the vulnerability of ecosystems such as the marshlands and river environments. Strengthening biodiversity conservation, managing natural resources sustainably, and supporting scientific research are essential steps toward maintaining ecological balance and ensuring environmental sustainability for future generations. Al-Mustaqbal University – The First University in Iraq