Another important concept concerning all three curves is that their scope is the development of major release of a system. Following the traditional approach some systems are released once and then bug fixes are applied over time via patches. Other times an incremental approach is taken where major releases are developed and deployed every year or two. With an agile approach an incremental approach is typically taken although the release timeframe is often shorter - for example releases once a quarter or once every six months aren't uncommon, the important thing is that your release schedule reflects the needs of your users. Once the release of your system is in production the cost of change curve can change. Fixing errors in production is often expensive because the cost of change can become dominated by different issues. First, the costs to recover from a problem can be substantial if the error, which could very well be the result of a misunderstood requirement, corrupts a large amount of data. Or in the case of commercial software, or at least "customer facing" software that is used by the customers of your organization, the public humiliation of faulty software could be substantial (customers no longer trust you for example). Second, the cost to redeploy your system, as noted above, can be very large in some situations. Third, your strategy for dealing with errors affects the costs. If you decide to simply treat the change as a new requirement for a future release of the system, then the cost of change curve remains the same because you're now within the scope of a new release. However, some production defects need to be addressed right away, forcing you to do an interim patch, which can clearly be expensive. When you include the cost of interim patches into the curves my expectation is that Figure 1 will flatten out at the high level that it has reached and that both Figure 2 and Figure 3 with potentially have jumps in them depending on your situation.
During the past century, human activities have released large amounts of carbon dioxide and other greenhouse gases into the atmosphere. Most of the gases come from burning fossil fuels to produce energy. Greenhouse gases are like a blanket around the Earth, trapping energy in the atmosphere and causing it to warm. This is called the greenhouse effect and it is natural and necessary to support life on earth. However, while greenhouse gases buildup, the climate changes and result in dangerous effects to human health and ecosystems. People have adapted to the stable climate we have enjoyed since the last ice age which ended several thousand years ago. A warmer climate can bring changes that can affect our water supplies, agriculture, power and transportation systems, the natural environment, and even our own health and safety. There are some climate changes that are unavoidable and nothing can be done about it. For example, carbon dioxide can stay in the atmosphere for nearly a century, so Earth will continue to warm in the future.