Concentrations are measured in parts per million (ppm), parts per billion (ppb), or parts per trillion (ppt) 1 ppm for a given gas means, for example, that there is one molecule of that gas in every 1 million molecules of air. The first is how much of it exists in the atmosphere. How much any one greenhouse gas influences global warming depends on three key factors. Fluorinated gases are destroyed only by sunlight in the far upper atmosphere.
Carbon dioxide, for example, is absorbed by so-called carbon sinks such as plants, soil, and the ocean. Greenhouse gases have different chemical properties and are removed from the atmosphere, over time, by different processes. The main gases responsible for the greenhouse effect include carbon dioxide, methane, nitrous oxide, and water vapor (which all occur naturally), and fluorinated gases (which are synthetic). The higher concentrations of greenhouse gases-and carbon dioxide in particular-is causing extra heat to be trapped and global temperatures to rise.Įarth’s greenhouse gases trap heat in the atmosphere and warm the planet. (In other words, there were 200 to 280 molecules of the gases per million molecules of air.) But in the past century, that concentration has jumped to more than 400 parts per million, driven up by human activities such as burning fossil fuels and deforestation. While some of this infrared light continues on into space, the vast majority-indeed, some 90 percent-gets absorbed by atmospheric gases, known as greenhouse gases, and redirected back toward the earth, causing further warming.įor most of the past 800,000 years-much longer than human civilization has existed-the concentration of greenhouse gases in our atmosphere was between about 200 and 280 parts per million. This heat is then radiated back up in the form of invisible infrared light. While 30 percent of the solar energy that reaches our world is reflected back to space, approximately 70 percent passes through the atmosphere to the earth’s surface, where it is absorbed by the land, oceans, and atmosphere, and heats the planet. Identified by scientists as far back as 18 96, the greenhouse effect is the natural warming of the earth that results when gases in the atmosphere trap heat from the sun that would otherwise escape into space. Here’s a look at what the greenhouse effect is, what causes it, and how we can temper its contributions to our changing climate. The result? An increase in global warming that is altering the planet’s climate systems in countless ways. The problem is, mankind’s voracious burning of fossil fuels for energy is artificially amping up the natural greenhouse effect. Without it the world would be a frozen, uninhabitable place, more like Mars. It warms the planet to its comfortable average of 59 degrees Fahrenheit (15 degrees Celsius) and keeps life on earth, well, livable. The Consequences of the Greenhouse Effect.The latest research and techniques are used to produce healthy plants and flowers grown for arrangements when the cutting garden is not in bloom. Wander in and you’ll likely find a knowledgeable staff member or volunteer applying their knowledge to the care of these exotic plants. area that offers visitors daily access to a working greenhouse where orchids and other tropical plants fill the space with color and fragrance. Hillwood is one of the only public gardens in the Washington, D.C. Today, Hillwood maintains the orchid collection to Post’s exacting standards, with a collection of over 2,000 specimens and hundreds of different varieties, and carries on the tradition of filling the mansion with these exotic flowers.
Post was so fond of her orchids that she often had a large selection shipped from Hillwood to grace her rooms when she was in residence at her other properties. Freshly cut orchids were also used in many of the floral arrangements for special events that she hosted. The curator delivered orchids in bloom to the mansion, always displaying them in Post's bedroom, the breakfast room, the library, and the French drawing room.
Post even hired an orchid curator to tend these temperamental beauties and breed new varieties for her pleasure. She saw Hillwood as a perfect opportunity to support her growing orchid collection and had four more greenhouses built on either side of the existing one. Orchids were her favorite flower and she invested significant resources into fueling this passion. When Marjorie Merriweather Post purchased Hillwood in 1955, a small greenhouse existed on the grounds. In any season, the beauty and serenity of fragrant flowers can be found in the greenhouse.